The British Rail Class 29 consisted of 20 diesel locomotives which were rebuilt from the North British Class 21 in 1964-1965 at Polmadie Works with a Paxman'Ventura' V12 engine (predecessor to the HST 12RP200'Valenta' engine).
The British Rail Class 29 consisted of 20 diesel locomotives which were rebuilt from the North British Class 21. The original license-built MAN engines of the Class 21s had proved unreliable, so in 1963 locomotive D6123 was dispatched to Paxman's Colchester works to receive a new Paxman' Ventura'V12 engine (predecessor to the HST 12RP200' Valenta' engine).