British Rail Southern Region conversion
3R Units
(Nos. 1201 to 1206)


6B 1036 & 3R 1202 @ Tonbridge copyright BloodandCustard.JPG

In the company of 6B unit 1036 at Tonbridge 3R ‘Tadpole’ unit 1202
(with blue /grey motor coach) awaits departure for Redhill and Reading.
The inverted black triangle provided an early indication to station
staff that there was
no brake van at the other end of the unit.

© BloodandCustard


‘Tadpole’ diesel units

The 3R ‘Tadpole’ units were interesting hybrid units on the Southern Region’s Reading – Tonbridge line although they did at times see very limited use elsewhere, including Hailsham to Eastbourne, the Oxted line (including Tunbridge Wells West).  For example, 1204 was observed at Henfield on a Brighton to Horsham working and on 6th January 1965 an unidentified 3R was seen working part of the 18:10 Victoria to Brighton (via Uckfield).

For a year in 1979 Tadpole units worked through from Reading to Basingstoke and on a Saturdays-only service from Reading to Basingstoke & Salisbury. At the end of its life unit no.1206 was allocated to work Hastings to Ashford.

They have also been seen on passenger services between Portsmouth and Salisbury as well as the Swanage Branch 1st July 1967 (unit 1201), Henley-on-Thames to Paddington (19th April 1972 unit nos. 1202 & 1203 during a ‘work to rule’ by BR staff) and Reading to Oxford (engineering works on 10th & 17th July 1979).


Creation of a Hybrid

The Tadpoles came about from a need to withdraw steam operation on the Reading – Tonbridge line and to introduce ‘Paytrain’ operation with the ‘R’ coming from Reading /Redhill. However, the 3H and 3D units were not gangwayed within each set and so were considered unsuitable; furthermore the cost of a new built of diesel trains could not be justified.

Accordingly it was decided to disband three 6S Hastings units (1002, 1003 and 1004) and utilise their DMBSO and TSO (along with some EPB driving trailers) to form six three-car 3R units. This was undertaken at Wimbledon and Ashford Chart Leacon depots during November 1964.


1202 Shalford 1Jan75 Scan-150111-0001.jpg

Unit 1202 departing Shalford for Tonbridge on 1st January 1975
© Dave Smith


The (former) 6S Vehicles (DMBSO & TSO)

The engines were up-rated to 600 bhp to match the 2H/3H and 3D units, this being achieved by replacing the original Napier MS100 turbochargers with the MS200 type. In view of the proposed high mileages a further modification took place during overhaul when the suburban type EE507D oil-lubricated traction motors were replaced with EE507E roller bearing suspension type.

Of the TSOs (diagram 670) the toilet compartments (and the three-bay) saloon were coupled next to the DMBSO; the four-bay saloon was designated non-smoking. None of the three seating bays in the DMBSO (diagram 650) were designated non-smoking.

When first formed each 75mph unit weighed 113 tons, was 186 feet 8.5 inches long with a maximum seating capacity of 140 second class passengers. Whilst in 6S unit no.1003, the motor coaches of 1203 and 1204 had missed out on the interior re-panelling at Lancing so retained their wooden interior panelling.

The Tadpole units were numbered 1201 to 1206 and because of the difference in width between the wider Restriction ‘4’ (C1) EPB coach and the two Restriction ‘0’ Hastings cars gained the nickname Tadpoles. Unlike most nicknames “Tadpoles” ended up appearing in official BR documentation. Under TOPS the units became class 206 although were not renumbered at this time.

Following conversion, the reformed units were run back to St Leonards depot for renumbering, engine changing and initial testing. Units 1205 and 1206 were reformed at Wimbledon Park depot, the first (1205) running to St Leonards on 24th November 1964. It is believed that one was displayed at Waterloo (with new 4 CIG unit 7301) on 6th November 1964.

The first test run on the Tonbridge - Reading line took place early in December 1964, and unit 1205 was used on the Oxted line on 12th December 1964. The units reformed at (Ashford) Chart Leacon were also ready in December 1964, unit 1203 running on test as a 2-car from St Leonards to Eridge via Heathfield on the 18th December 1964.

The displaced coaches following reforming at (Ashford) Chart Leacon were moved to Eastleigh as follows:

6th December 1964      65300 (5701) + 10207 & 10208 (both 4360) + 65307 (5708)
+ 60703 & 60511 (both 1004) + 60750 (1032) + 60755 (1031).
Hauled by D6551.

4th January 1965           65303 (5704) + 60701 (1002) + 60702 (1003) + 65308 (5709).
Hauled by Ashford-built N-class number 31816.

A number of the ‘Hastings’ coaches were mounted on bogies with shoebeams for these movements, these being swapped from the 2 EPB coaches used in the 3R units.


1201 roof Scan-140216-0014.jpg

Roof detail of DMBSO 60002 unit 1201
near Betchworth 20th December 1974

© Dave Smith


3R roof Scan-140216-0013.jpg 

Roof detail of DMBSO 3R unit
near Betchworth 20th December 1974

© Dave Smith


1202 roof Scan-140216-0001.jpg

Roof detail of TSO 60504 unit 1202
near Betchworth 20th December 1974

© Dave Smith


3R roof Scan-140216-0015.jpg 

Roof detail of TSO 3R unit 1202
near Betchworth 20th December 1974

© Dave Smith

BloodandCustard makes no apology for the repetitive nature of these rare superb roof detail
photographs courtesy of Dave Smith© as they will be of considerable interest to the modeller;
in particular the differing types ventilators on the TSOs plus the variation in body widths!


Tadpole Driving Trailer Seconds (DTS)

The Tadpole driving trailers came from a 1954 batch of BR design 2-EPB units (nos. 5701 – 5711) that had been built with headstocks to carry buckeye couplings and compression bars.  Unfortunately, it was realised that a 10-car EPB formation so coupled would not fit into Holborn Viaduct station and a decision was made to standardise on the SR practice of single buffers within EPB units thus reducing each coupling by some 8” in length. Only 5701 is understood to have been fitted with buckeyes and these were removed before it entered service. However, this did mean that these EPB driving trailers could be fitted with fixed-head buckeyes and compression bars with relative ease in order to couple with the Hastings cars.

Accordingly, the 2-EPB nos. 5701 /5704 /5708 /5709 /5710 & 5711 were disbanded with the EPB motor coaches being reformed into three 4-EPB units using SR design trailer cars, whilst the driving trailers were converted to DEMU operation. Still retaining their designation of diagram 420, the driving trailers comprised 4-bay saloon and 5-compartments. Three of the compartments (those furthest from the driving cab) were gutted and re-panelled to form additional van space primarily for the mail traffic between the mail centres on the line. The windows (but not droplights) in these 7-ton mail areas each had two vertical bars fitted.

This left 66 seats for passenger use (42 in the open saloon plus two 12-seat compartments) although during some quieter periods even these seating areas were locked out of use so as to concentrate passengers into the two gangwayed coaches. Certainly, the two passenger compartments (between the mail area and passenger saloon) did at one point have door markings ‘C1’ and ‘C2’ and were occasionally locked out of passenger use to enable their use for the carriage of mail; the compartment next to the mail area being designated non-smoking. The former 6S ‘Hastings’ coaches seated 52 and 22 passengers respectively.

Besides the controller change (omission of EPB controller notches 2, 4 and 6) the Mk3D bogies (a modification of the original Mk2A bogies) were replaced with Mk4 bogies similar to those already fitted to DEMU coaches as roller bearings were deemed necessary for the high mileages proposed; around 11,000 miles every four weeks. The Tadpoles were the Southern’s 4th highest mileage unit and highest mileage demu; unsurprising there were instances where they ran out of fuel!

Other alterations required were the removal of shoe gear /shoe beams & power cabling, circuit adaption from 70v to 90v operation (including light bulbs) and the rewiring of the jumper cabling /provision of demu jumpers at the inner end.

When some of the driving trailers were subsequently reused as non-driving trailers in the Hampshire units further work was undertaken to make the driving cabs inoperable; their yellow ends were painted plain blue.


1202 roof Scan-140216-0016.jpg

Roof of DTS 77503 unit 1202
near Betchworth 20th December 1974
© Dave Smith


Re-deployment of the 2-EPB Motor Coaches

Following the formation of the Tadpole units the 2-EPB motor coaches 65300 and 65310 from 2-EPB units 5701 and 5711 along with two ex-Sub augmentation trailers (so both had trailers had compartments) were formed into 4-EPB no. 5261.

Motor coaches 65303 and 65308 from 2-EPB units 5704 and 5709 along with one ex-Sub augmentation trailer and a spare SR EPB trailer were formed into 4-EPB no. 5262.  This unit was later reformed with SR EPB motor coach 14205 in place of 65308, which went to 4-EPB no.5302.

65307 from 2-EPB 5708 was used to replace a damaged motor coach in 4-EPB unit no.5247. Later on 65307 went to 2-EPB unit no.5769 to replace a motor coach written off in a collision.

Only 2-EPB unit no.5710 was reformed with 65309 coupled to spare driving trailer 75636. 


Tadpole Timetable.jpg

Original 1965 Timetable


Reading – Tonbridge Operations

The first Tadpole test run on the Reading to Tonbridge line took place early December 1964 and unit no.1205 was test run on the Oxted line on 12th December 1964.

First passenger use on the Reading to Tonbridge line took place on 3rd January 1965 with positioning trips taking place for the introduction of diesel services on 4th January 1965. It must be noted that some trains were diesel locomotive hauled both before and after this date – the last being around 1977/78.

However, on 6th January 1965 it was reported that a Tadpole unit worked the 6.10pm Victoria to Brighton service!

Tadpole Route.jpg

Route diagram contained within the new timetable


Tadpole Tickets.jpg

‘Tadpole’ service ticket promotion


It was proposed that Western Region paraffin cans would work the Reading – Tonbridge line so during the late 1970s a decision had been made to disband four of the 3R sets, starting with reformation of 6S unit 1002 and when 6L unit 1032 collided with the buffer stops at Charing Cross (11th January 1979) changes and withdrawals started to take place.

Although class 101 Metro-Cammell units started working on the Reading – Tonbridge line from 5th February 1979, the Redhill’s mail traffic soon lead to their replacement with class 119 Gloucester RC&W units which had larger lockable luggage cages; their steady introduction onto the line leading the rapid demise of the 3R sets.

Thereafter regular 3R unit usage was left to the Ashford – Hastings service.


3R 1206 at Ashford.jpg

Still relatively new to the Ashford - Hastings line
unit 1206 awaits departure from Ashford

© BloodandCustard



On 26th June 1971 unit 1205 historically operated a shuttle ‘railtourcompring a dozen return trips from Brighton along Brighton’s Kemp Town branch in order to mark the line’s closure. An inverted black triangle was not carried on 1205 at this time.

The only other known ‘Tadpole’ railtour was with 1203 & 1206 on the Southern Electric Group’s ‘Inter-Village Express’ on 6th May 1979. This ran from London Bridge to Brighton, Eastbourne and Hastings where unit no.1204 replaced a failing 1206. After the substitution the tour continued on to Ashford, Tonbridge, Redhill, Reading, Kensington Olympia and Blackfriars before returning to London Bridge.


3R 1206 leaving Ashford.jpg

In torrential rain unit 1206 departs from Ashford.
Note at this point it retains its 6S motor-coach.

© BloodandCustard



Like the remainder of the BR(S) diesel-electric multiple-unit fleet these units were prohibited over the following routes and sidings (correct to 6th May 1968):

Shepherds Well - Tilmanstone Colliery
Portsmouth & Southsea – North Dockyard Line
Isle of Wight Lines
Littlehampton Wharf Line

Diesel-electric units could only work in multiple with other diesel-electric units.



Tadpole Liveries

Tadpoles and the Inverted Black Triangle

The mail area in the DTS did lead to some confusion in respect of placement of the black inverted triangle on the front of the motor coach. Fitted to two and three car multiple BR(S) units this triangle denoted that there was no brake van at the other end of the train and followed the orange-Vees originally fitted to the 2H & 3H units, but not the 3D ‘East Sussex’ sets and for the Tadpole units it is relevant to understand the original imperative behind the need to indicate this.

The imperative for the orange ‘Vee’ is believed to come from mail pick-ups at Winchester City following the introduction of 2H /3H units on the Alton to Southampton services. These units only had a brake van at one end (the motor coach) whereas the steam hauled carriage sets had brake vans at each end with the guard riding in the rear.

Postal staff would traditionally be waiting to load mail into the rear of the train but with a 2H/3H unit the only brake van might arrive at the front of the unit. As a consequence this could cause service delays as postal staff had to move the mail along the platform to the front of the train.

Accordingly the orange-Vee would provide an early indication to staff that there was no brake van at the other end of the unit.

As this problem did not exist on the Central Division the 3D ‘East Sussex’ units (latterly referred to as ‘Oxted’ units) were not equipped with orange-Vees.

It is believed that unit 1102 was the first to be equipped in 1960; 1111 being the first to receive an inverted black triangle in 1965 which provides an indication towards the application of yellow waring panels on 2 & 3-car demus. In terms of the carriage of mail the brake van provision on 2H /3H units wasn’t generous and on later 3H ‘Berkshire’ builds a seating bay was sacrificed to provide a larger baggage area.

With the introduction of small warning panels (trialled on BR(S) in 1962, the first 2-EPBS started received theirs in late 1963 (1964 saw a great rush to equip most units) the first demu may have been in 1965) a decision was made to replace the orange-Vee with a black inverted triangle and that this useful indicator to staff should become standard for all 2 and 3-car demu /emu stock on the BR(S).

This caused some confusion on the Tadpole units as the “postal area” was in the DTS; most mail was carried here and not with the guard in the motor coach. As a consequence some motor coaches ran for a period (in blue livery) without the inverted black triangle (an example being 1202 in September 1968 and 1205 in 1971).

However, the “postal areas” in the DTS were generally only used at the mail centres (such as Redhill) where the timetable allowed for the loading of mail. At intermediate stations the guard would have had to walk the length of the train (and back again) to access the DTS leading to additional dwell time and by now the inverted black triangle provided a useful indicator to staff (and passengers in the know) for the loading of other items such as perambulators.

Examples of units carrying an inverted black triangle were 1201 (period unknown), 1202 (1971 & 1972), 1203 (November 1970 & May 1979), 1204 (July 1979) & 1206 May 1979.

Tadpole cars have been seen in Hastings units. For example, following the Appledore derailment on 14th March 1980 there was a dire shortage of Hastings cars and so Tadpole unit no.1205 and 1206 were disbanded. As a consequence, a blue /grey 1001 was temporarily reformed with an all-over blue Motor Coach still carrying 1206 and the inverted black triangle (certainly on 24th March 1980). 

In addition, Hastings units (compared to Tadpole numbered vehicles) have been seen with inverted black triangles such as 1003 in June 1980.


Green Livery

When formed, all units were green. Units 1203 and 1204 did not have yellow panels on their motor coaches although their Driving Trailer Seconds did have yellow panels; unit no.1202’s motor coach didn’t receive its warning until 4th July 1966; 1204 received its on 15th June 1966. However, it is believed that units 1201, 1202, 1205 and 1206 had yellow panels both ends from new.



Unit 1206 near Tonbridge.
© BloodandCustard


All-over Blue Livery

Following the introduction of ‘corporate blue’ in 1965 the Southern started painting some multiple units plain blue in 1966 although some dates for repainting the 3R sets into all-over blue with full yellow ends are currently uncertain, the following is known:

1201 - 16th June 1967

1202 – 20th April 1967

1203 – 27th March 1969

1204 – 10th April 1969

1205 - by September 1968

1206 - November 1967.

1202 was the first to ‘go blue’ in April 1967. It had the smaller numerals and small BR double arrow set higher up than standard. 1202’s underframes were brown and there wasn’t an inverted black triangle on the motor coach. Around 1970 unit no.1202 was repainted (blue) and gained the standard numerals, a BR double arrow in the normal position and an inverted black triangle.

1201 was the second to be painted blue (16th June 1967). It had larger numbers, BR double arrow set lower down and a black inverted triangle on the motor coach.

1206 was the third (by November 1967) and 1205 the fourth (c.August 1968); both without inverted black triangles on the motor coaches. Unit no.1206 received an inverted black triangle when it was repainted at Swindon, possibly around 1970.

1203 was fifth (c. May 1969) and 1204 the sixth (c. June 1969); both had inverted black triangles on their motor coaches. Unit no. 1204 may have been last having received a ‘green’ repaint in June 1966.


Blue-Grey Livery

Of the original formations only 1206 didn’t have its 'Hastings' coaches painted blue grey whilst formed as a ‘Tadpole’ being removed earlier in the year.


(both coaches) was repainted in December 1978 with an inverted black triangle;


(motor coach) painted September 1978 (without inverted black triangle) anticipation of re-use in 6S 1002; the TSO and DTS retaining all-over blue livery. However, in January 1979 1202’s trailer second (60504) was temporarily replaced by 60551 whilst 60504 was repainted blue /grey reappearing within unit no.1202 by 23rd March 1979.


(both coaches) was repainted in March 1979 with an inverted black triangle;


(both coaches) was repainted in March 1979 with an inverted black triangle;


(both coaches) was repainted in September 1979 but without the inverted black triangle;


went to works blue November 1980 and the two 'short' Hastings coaches were removed from the unit and painted blue/grey ready for use in 6S unit.1004. Not long afterwards the driving trailer second (DTS 77510) of unit no.1206 received blue /grey livery (certainly by November 1981).


1203 Redhill 28Mar73 Scan-150111-0002.jpg 

Unit 1203 awaiting departure from Redhill’s platform 1 on 28th March 1973
The inverted black triangle provided an early indication to station
staff that there was
no brake van at the other end of the unit.
© Dave Smith


Tadpole Formations

Unit 1201

Formed January 1965

DMBSO 60002

TSO 60503

DTS 77500

Disbanded 12th May 1979.




DTS 77508 went to augment 2H ‘Hampshire’ unit no.1108 into 3T unit no. 1401.


Unit 1202

Formed January 1965

DMBSO 60003

TSO 60504

DTS 77503

October – November 1974

DMBSO 60009#1

TSO 60504

DTS 77503

January to March 1979

DMBSO 60003

TSO 60551#2

DTS 77503

Disbanded 12th May 1979.




DTS 77503 went to augment 2H ‘Hampshire’ unit no.1104 into 3T unit no. 1404.


DMBSO came from 6S unit 1005


Long vehicle (ex.6B 1031)


Unit 1203

Formed January 1965

DMBSO 60004

TSO 60505

DTS 77507

Disbanded May 1979.




DTS 77507 went to augment 2H ‘Hampshire’ unit no.1103 into 3T unit no. 1403


Unit 1204

Formed January 1965

DMBSO 60005

TSO 60506

DTS 77508

March to August 1979

DMBSO 60002

TSO 60551*

DTS 77508

Disbanded 8th August 1979.




DTS 77508 went to augment 2H ‘Hastings’ unit no.1122 into 3T unit no. 1402.


Long vehicle ex.6B 1031


Unit 1205

Formed January 1965

DMBSO 60006

TSO 60509

DTS 77509

Out of use from March to July 1980.

Disbanded October 1980.




Moved to Mayer Newman, Snailwell for scrapping 25th September 1987 arriving there 29th September 1987 and burnt 13th October 1987.


Unit 1206

Formed January 1965

DMBSO 60007

TSO 60510

DTS 77510

During January 1976

DMBSO 60016#1

TSO 60510

DTS 77510

From January 1976

DMBSO 60007

TSO 60510

DTS 77510

From November 1980

DMBSO 60037#2

TSO 60702#3

DTS 77510

Disbanded April 1983
Reformed January 1984
Disbanded March 1984.




Unit moved to Mayer Newman, Snailwell for scrapping 25th September 1987 arriving there 29th September 1987 and burnt 5th October 1987.


Long vehicle no.60016 ex.6L 1012




Long vehicle no.60037 ex.6B 1033




TCK (downgraded TFK ex.6S 1003





‘Tadpole’ Style Reformations

Unit 1309 (3D)

During the mid-1980s blue /grey 3D unit had its motor coach replaced with blue /grey 6L motor coach no. 60045 gaining the unofficial nick-name of a ‘Fat Tadpole’. By 1986 the 3D trailer composite also gained blue /grey livery and by April 1987 the driving trailer was also blue /grey. Numbered 207009, an inverted black triangle was not carried.


Unit 1319 (3D)

Unit 1319 was involved in a collision at Selhurst depot 10th November 1985 and MBS 60144 damaged. The MBS was replaced by ‘Hastings’ MBS 60044 (ex-disbanded 5L 1037) from November 1985 to 25th March 1986 when 60144 returned after repairs using cab of withdrawn 60134 (ex-1309).


Unit 1107 (3H)

The MBS 60106 of unit 1107 was condemned 25th July 1985 due to severe roof corrosion and defective door pillars; this being replaced by blue /grey 6L motor coach Hastings MBS 60037 (ex. disbanded 3R 1206) this coach seating 30 giving a unit total of 19 first and 184 second and gaining the unofficial nick-name of a ‘Fat Tadpole’..

MBS 60037 was condemned 7th Apr 1986 and stored at Mountfield thence to Chart Leacon for stripping 17th July 1987. Moved to Mayer Newman (Snailwell) from Tonbridge 2nd October 1987 arriving 16th November 1987 and burnt 18th March 1988. Replaced in unit by similar 60022 (ex-disbanded 6L 1015) and renumbered 205007 on 5th October 1987.

Unit withdrawn 5th October 1987 and moved to Chart Leacon for bogie recovery. MBS 60022 hauled to Selhurst for engine recovery 26th February 1988 before returning to Chart Leacon 12th January 1989 thence to Ore for storage. Moved to Sevenoaks September 1989 before leaving Sevenoaks 30th October 1989 for scrapping by V. Berry, Leicester.


Unit 1113 (3H)

On 31st May 1985 unit 1113 was damaged in a collision with a Railair set at Battersea Park and withdrawn. Following a period in store at Selhurst depot, it was moved to St Leonards for stripping 27th January 1986 with MBS 60112 & TS 60662 both condemned and after storage taken to Mayer Newman (Snailwell) for scrapping; arriving there 16‑Nov‑87..

However, unit 1113 was reinstated from April 1986 using two ex-6-car Hastings vehicles from disbanded 5L 1037 MBS 60044 (then running in 3D 1319) & TSO 60561. Unit still numbered 1113 but now reclassified as Class 206. Seating 19 first /140 second and used mainly on Ashford to Hastings route.

When all the units were renumbered this unit became 206101 from August 1986.

Unit was withdrawn 5th October 1987 and after stripping at St Leonards moved to Mountfield for store thence to Chart Leacon for bogie recovery 27th November 1987. Then stored at Sevenoaks, moving from Chart Leacon 11th January 1988. Hauled to Mayer Newman (Snailwell) for scrapping 11th March 1988, arriving 14th March 1988. Coaches burnt as follows: 60812 15th March 1988, 60561 16th March 1988 and 60044 8th April 1998.




3R Preservation

It is not without irony that the Tadpole spirit lives on in preserved Hastings unit 1001 which currently comprises two Hastings 6L motor-coaches paired to two Hastings (6L & 6S) trailer seconds currently sandwiching two Restriction ‘4’ electric multiple unit coaches. Within this set the 6L motor coach 60016 (currently numbered 60116 under TOPS) powered 3R unit 1206 during January 1976 and is the only coach used in a 3R unit (albeit so very briefly) to survive. Sadly it is understood that none of the ex-EPB driving trailers were preserved.

Q Nene Machine 055.jpg

Hastings Motor Coach 60016 is the only surviving vehicle to be used (briefly) in
a 3R unit (during January 1976); now running in preserved Hastings unit 1001

© Colin Watts


The 3R in Model Form

Currently the DC kits 4mm kit no longer appears to be available.
A proposed conversion kit utilising the Bachmann EPB never materialised.



Thanks go to Messers Atkinson, Beecroft, Standen and Watts.

Photographs © courtesy of Dave Smith and Colin Watts.


If any reader has more information on Tadpole units then please do let www.BloodandCustard.com know!