1/3. The Fell diesel-mechanical prototype locomotive (numbered 10100 by British Railways) at Derby. Probably a loco my father helped to design British Railways 10100 was an unusual experimental diesel locomotive known informally as The Fell Diesel Locomotive. Experimental LMR Diesel-Mechanical 4-8-4 at Derby. . LMS/Fell 2-D-2 Diesel-Mechanical No. 10100 was designed as a prototype 2,000hp locomotive and built in 1950, but only began trials in 1/51. In 1/52 it began scheduled work on passenger trains between Derby and Manchester Central by the Peak Line: it continued, with some prolonged interruptions, on this line until it broke down in 10/58 and was withdrawn, but it was not scrapped until 7/60. Although a comparative success, the design was not perpetuated. 4. LMS / Fell experimental Diesel Loco 10100 at Derby Loco works after a fire in 1958, thereafter withdrawn.