British Rail Class 97

British Rail reserved the TOPS Class 97 designation for departmental locomotives, which were used for special or engineering duties. They were therefore of several different classes, lumped together for numbering purposes. Some locomotives were converted from redundant engines, whilst others were purpose built. In 2008, Network Rail once again used Class 97 for signalling test locomotives (Class 97/3).

Class 97 numbers were allocated in one of three ways:

Built by Ruston & Hornsby in January 1957 with the serial number 408493, this 0-4-0 shunter was ordered specifically for departmental use by the Signalling & Telecommunications department of the Western region at Reading Signal Works. The transmission was diesel mechanical, although the wheels were chain driven from the gearbox and the loco was rated at 88 bhp (66 kW) for a weight of only 17 tons. Tractive effort was a maximum of 9,500 lbf (42,000 N). Delivered to the WR with the number 20 it was renumbered to 97020 in May 1980. However withdrawal came in April 1981 and it was scrapped on site in August 1982 by Cartwrights of Tipton. For refuelling, it had to go via the main line to the depot at Reading.

This locomotive was a former Class 24 locomotive, which was taken over by the Railway Technical Centre, based at Derby, in 1975. It was initially numbered RDB 968007, and was given its Class 97 number in 1979. It was employed hauling various test-trains until retirement in 1988. It was painted in RTC's distinctive red/blue livery, and named "Experiment". After withdrawal it was preserved on the North Yorkshire Moors Railway.

This was former Class 25 locomotive 25131 used for training purposes at Toton depot. It had been withdrawn on 6 December 1982 and was reinstated as 97202 on 1 October 1983. It only lasted in Departmental service until January 1984 when it was again withdrawn, eventually being scrapped by Vic Berry.

Subsequently, other training locomotives were numbered in the ADB 968xxx series.

...
Wikipedia