List of British Rail power classifications

The British Transport Commission, later British Railways, used engine power output to categorise its new main line diesel locomotive fleet following the 1955 modernisation plan. These categories were from Type 1 to Type 5 and are listed below. 
Type 1.
Up to 1,000 bhp
Type 2.
From 1,001 bhp to 1,499 bhp
Type 3.
From 1,500 bhp to 1,999 bhp
Type 4.
From 2,000 bhp to 2,999 bhp
Type 5.
From 3,000 bhp