The entire class of 19 three car units was built in 1962 for the Oxted line. They were originally formed motor brake second saloon (MBSO), trailer composite lavatory (TCL) and driving trailer second semi-saloon (DTSO). The MBSO contains an 8ft 2in guard's and luggage compartment. They are similar to the earlier 3H units although there are a number of differences. The cab ends made of steel reinforced fibreglass are similar to contemporary EMUs such as 4 Cigs. The driver's desk is also to a revised design. Being built to run between Tonbridge and Tunbridge Wells West, a route notorious due to its Somerhill Tunnel with restricted clearance, the bodywork is built to 8ft 6in width. Although their engines are of the same type as other Southern Region DEMUs their mounting arrangements are different and thus they are not readilyinterchangeable.

There have been reformations over the life of the class. In later years they were been reformed as standard class only 2 car sets (class 207/0) and 3 car (207/2) containing a former refurbished 4 Cep trailer second (TS) released by withdrawal of the Cep units and reformation to 3-Ceps. In this latter case the difference between body widths is obvious. With the diminution of work for DEMUs on the former Southern Region their sphere of operation has also increased to take in the Ashford to Hastings "Marshlink" line. In terms of surviving in quantity the 207s have fared slightly less well than the earlier 205 DEMUs with only 4 units (one 205/0 and three 205/2) - 21% of the original fleet - remaining by 2001.

BR built one later design of DEMU, the experimental class 210, to a Mk3 design. Only two such units were built and tested, the intention being to replace heritage DMUs particularly on the Western Region. The design proved too expensive for mass production and what eventually emerged were the "Sprinter", and later "Turbo", DMU classes.

The only other widespread use of DEMU traction in the British Isles is in Northern Ireland where NIR use DEMUs originating from BR Mk2 and Mk3 designs. The NIR 450 class DEMUs, to a Mk3 design, demonstrate what could have happened on the mainland - there is more than a slight resemblance to a Southern class 455 EMU and the class 210.