Class 24 and class 25 diesels.

The British Railways class 24 diesel locomotives, also known as the Sulzer Type 2 or BR type 2, were built from 1958 to 1961. One hundred and fifty-one of these locomotives were built at Derby, Crewe and Darlington, the first twenty of them as part of the British Railways 1955 Modernisation Plan. They had a power rating of 1160 bhp.

The original locomotives had disk headcodes, later ones had the 4-character roof box displays.

The class was developed into the class 25 locos with an increase in power to 1250 bhp and a top speed of 90 mph compared to the class 24's. The first class 25's had a more angular roof headcode box compared to the class 24's and originally retained the communication doors on the front, but this was removed in later builds resulting in 3 large windows at the fronts. Both classes were affectionately known as 'rats'.

In this video we see preserved examples of class 24 and 25 locos, mainly on the North Yorkshire Moors Railway, but also an earlier version of the class 25 on the North Norfolk Railway.

Only 1 loco is main line registered (D7628) and this is limited to the line into Whitby from the North Yorkshire Moors Railway.