Built by British Railways at Derby in 1959 this Driving Motor Brake coach is an example of  the long-wheelbase suburban design, which had high-density seating and more doors to each coach to facilitate loading and unloading. As such it is different to all the other vehicles in our collection.
It is also fitted with an unusual mechanical configuration consisting of two underfloor Rolls Royce 238bhp eight-cylinder engines which drive the wheels through torque convertors, therefore not requiring a conventional gearbox. This arrangement was to become very common on DMUs built after 1984, so this train could be said to have been over 20 years before its time.
Introduced for the Bedford to St Pancras service in 1959 this car ran as part of a four-car set. It remained on these duties until 1984 when the line was electrified and was then withdrawn along with the rest of the power cars, which were worn out. Almost immediately it was saved for preservation and moved to Llangollen, where it has worked now for longer than it did on the main line.

The car is from lot number 30521.

In 2009 51618 was repainted in Medium Brunswick Green livery. The relivery was completed in 2010 when the roof was fully repainted in grey gloss and the white headcode box was reinstated. During this period the roof was extensively repaired, particularly around the gutter and cab areas. The latest livery coincided with 51618 being allocated a different trailer to the one which it had hauled between 1984 and 2009. It currenly is in regular service partnered with class 108 trailer 56223.
 

Between 1986 and 2009 51618 ran with Cravens trailer 56456 and in this period the unit carried Deep Brunswick Green livery. The unit was extensively renovated in 1990 and 1997 and had the interior retrimmed in 2000. One of the engines was replaced with a reconditioned unit in 1997 while the second engine was reconditoned in 2007. Also replaced in 2007 was one of the final drives, which had failed in service. Between 1986 and 1994 this was the only power car on the Llangollen Railway and was worked very hard and as a result it has required considerable attention to bring it to an acceptable standard.

When initially delivered to Llangollen in 1984 51618 ran in its as-withdrawn British Rail blue livery and was used on many of the early services of the Railway. As extensions were built it was inevitably the first form of traction used as it did not need a run-round loop, therefore it was the first train across the Dee Bridge and the first to take passengers to Berwyn. During this period some of the doors were taken out of use and some of the footboards were removed, although this was reversed in the early 1990s. Corridor connections were added to the coach ends and a connection made to the saloon, enabling passengers to walk the length of the coach and move into the adjacent vehicle.