BR/Leyland

'BR/Leyland' is used in this encyclopedia for the joint design and construction programme between British Railways and Leyland Vehicles (latterly Leyland Bus) of Workington and Wolverton, which produced the Class 140 prototype 'Railbus' of 1981 and the production Class 141, 142, 143, and 144 Pacer diesel railbuses of the early 1980s — one of the most controversial rolling stock procurement decisions in the history of British Railways.

The Pacer concept arose from BR's urgent need to replace ageing first-generation diesel multiple units on lightly-used regional services at minimum cost. The BR/Leyland solution was to mount Leyland National bus body shells on four-wheel rail underframes, producing a vehicle that was far cheaper than a purpose-built railway DMU but whose bus-body ride quality and noise levels were immediately unpopular with passengers and railway staff alike. The 'Nodding Donkey' or 'Pacer' nickname was not entirely affectionate.

Despite their poor reputation, the Pacers served on BR and subsequently privatised operators for over thirty years, demonstrating a durability that belied their basic construction. 142 were eventually built in four variants, serving on Northern, Wales & Borders, and other regional routes well into the twenty-first century. Withdrawal came finally not from mechanical failure but from the requirement to make all passenger trains accessible to disabled passengers — the bus-derived body steps made step-free boarding impossible to retrofit, and a Government mandate forced their withdrawal by 2020. Three examples are preserved.