The six principal classes of diesel locomotive that once made up the `Type 4' classification - the 40, 44, 45, 46, 47 and 50 - were the survivors of a wider group that can trace its origins to the British Transport Commission's Modernisation Plan of 1955. Designating a power output of between 2,000 and 3,000 hp, the type once contained representatives of several non-standard and one-off prototype builds, including the Warship and Western diesel-hydraulics, which between them originally numbered over 100 examples. The scrapping, exporting or accidental writing off of the numerous Type 4 prototypes in the 1960s and early 1970s - with the exception of the ten Class 44 Peaks - left a cohort of over 900 diesel-electrics that became the real backbone of the BR fleet, including the most numerous single mainline class ever built in Britain, the `Brush 4' - or Class 47, as it later became.
This pictorial collection presents a wide-ranging selection of images of Type 4 locomotives from the late 1970s to the present day, photographed and compiled by Andrew Walker and John Walker with contributions from fellow photographer Vaughan Hellam.
Andrew Walker was born in Barnsley in 1962 and grew up in close proximity to the Penistone branch and to the Class 37s that operated over the line on daily trip workings to and from Wath up to the mid-1980s. He began photographing railways in 1978 and has contributed to many railway publications including a number featuring the Woodhead route, which he photographed extensively during its closing years.