'I remember how excited I was when I saw my first diesel. I was waiting for the usual West Country Class to come through Hampden Park when a Class 33 arrived instead. It was the talk of all the trainspotters at the junior school.' Author Mick Hymans' excitement soon turned to resentment as diesels replaced his beloved steam engines. They became rarer and rarer until in 1968 they disappeared altogether. Today the diesel engine enjoys a vast following in its own right. Preserved railways now run 'diesel days', steam-free days, which prove to be some of the most popular events in their calendars. Covering the whole railway system from the north of Scotland and Wales right down to Cornwall, British Rail Diesels presents a wide collection of photographs illustrating a lost world on the nation's railways.