The prototype for this was made on the same line as the Deltics, then in production. It differed from the standard Deltics in that it only had 1 engine, not 2. It became the forerunner for the Class 50 locomotives, the Deltics become the Class 55. This model is by the Danish company Heljan. I initially had a lot of problems with it derailing always at the same places. It turned out that the back-to-back wheel spacing on 1 axle was too small. Spreading the wheels out cured the problem and it is now a strong runner.