The British Rail Class 207 (3D) diesel-electric multiple units were built by BR at Eastleigh in 1962. The fleet had a lifespan of 42 years. The Southern Region class 201 to 207 DEMUs are nicknamed 'Thumpers' due to the noise their engine units make. Operational history When new the class were used on the Oxted Line, and were mostly concentrated on services between and Uckfield and Eridge to Tonbridge via . Other routes that the units operated included occasional workings on the Marshlink Line, the Three Bridges to Tunbridge Wells Central Line and the Cuckoo Line. Following the closure of the last two of these routes the unit gained workings on the Redhill to Tonbridge Line, and were known to deputise for 3R units on the North Downs Line to . Most units were withdrawn in 1987 following the electrification of the Oxted Line's branch. Four of the seven surviving units were used on the Reading to Basingstoke Line between 1988 and 1993; once this had finished three were withdrawn and the fourth sent to join the other three survivors on the Marshlink Line; between 1995 and 1998 this included through services from to . After this the class operated on the Marshlink Line between Ashford and and the Oxted Line between London Victoria and for privatised companies Connex South Central and Southern. The final three units were withdrawn in August 2004. Technical details Power car (one per set) Introduced: 1962 Weight: Engine: English Electric 4-cylinder type 4SRKT Mark II of at 850 rpm Transmission: Electric, two English Electric type EE507 traction motors rated at each. Maximum tractive effort: Driving wheel diameter: Coupling code: Standard 'Buck eye' compatible with contemporary Class 20x and 4xx units. Train heating: Electric Preservation Three complete units have been preserved: 207017 – Spa Valley Railway (3-car unit) 207202 – Formerly owned by Coulsdon Old Vehicle & Engineering Society, Bicester (2-car unit numbered 1305); purchased by and moved to the Bluebell Railway in January 2023. 207203 – Swindon and Cricklade Railway (2-car unit) – DMBSO 60127 damaged by fire on 20 May 2016. Class 205 DTCsoL 60822 will be added to replace DTSO destroyed by fire. This vehicle had been stored at Pershore (ex unit 1123) and arrived at the Swindon & Cricklade Railway on 17 June 2016. TS 60669 (ex unit 1124) also stored at Pershore arrived at the same time and will be stripped