that included salt for road gritting from the ICI mine at Winsford. The locos were selected from the available pool of Class 25 locomotives in March 1985 with the expectation of three more years of service before 10,000 running hours since last Works attention would be reached and their maintenance would be concentrated at Carlisle Kingmoor TMD. At that point the expected cascade of motive power on BR as a whole would see them replaced by Class 31 locomotives. However, the traffic they were designated for was not captured and in due course the sub-class were withdrawn along with the other members. Train Heating Units Three Class 25/3 locomotives were converted in 1983 at Aberdeen Ferryhill Depot for use as mobile generators to provide electric heating on trains where the hauling locomotive could not supply this. As part of the modifications the traction motors were removed and ETH sockets fitted. The engine was set to run at 640 rpm when providing heat, compared with the idle speed of 325 rpm, and the full engine speed on a non-modified Class 25 of 750 rpm. They were given departmental numbers 97250 / 97251 / 97252 (formerly 25310 / 25305 / 25314). They were referred to as ETHEL units (Electric Train Heating Ex-Locomotives), and unofficially named Ethel 1, Ethel 2 and Ethel 3. They were painted in a blue/grey livery in an effort to match the coaching stock livery of the day. After use in Scotland, two of the units (Ethel 2 and Ethel 3) moved to London for heating stock hauled by main line steam locomotives, and two were painted in the then current InterCity Executive livery (nicknamed 'raspberry ripple') to match BR's Special Trains Unit's Mk1 coaches. Ethel 1 was withdrawn in 1987, the other two in 1990. All three were scrapped in 1994. Prototype In 1962 Sulzer designed and began development of a prototype diesel engine for higher outputs based on the LDA range. Rated initially at at 850 rpm (with a development potential to at 850 rpm) it was approximately the same overall size as the 6LDA28 and designated LDA28-R. BR was approached with the idea that one of the Derby Type 2s should be fitted with this engine but development work proceeded slowly and problems with the 12LDA28-C (used on the Class 47 locomotive) diverted resources. In the end development was terminated and the locomotive set aside for