British Railways' Type 4 Warship class diesel-hydraulic locomotives were introduced in 1958. It was apparent at that time that the largest centre of expertise on diesel-hydraulic locomotives was in Germany. The Western Region of British Railways

Western Region of British Railways

The Western Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992...

 negotiated a licence with German manufacturers to scale down the German Federal Railway's "V200"

DB class V 200

DB Class V 200.0 was one of the first diesel-hydraulic express locomotives of the German Deutsche Bundesbahn and - as Am 4/4 - of the SBB-CFF-FFS in Switzerland.-DB Service:...

 design to suit the smaller loading gauge

Loading gauge

A loading gauge defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures...

 of the British network, and to allow British manufacturers to construct the new design.