Collection of approximately 260 cellulose nitrate film negatives and approximately 525 silver gelatin glass plate negatives by R F Dearden featuring locomotives and trains of the Great Western Railway, London and North Eastern Railway, London Midland and Scottish Railway, Southern Railway and British Railways, c 1934 to 1949, also known as the 'Main Line' Collection.

R F Dearden photographed Great Western Railway 'King', 'Castle', 'Hall' and 'County' Class engines at Twyford East signal box, Sonning Cutting, Waltham, Ruscombe, Maidenhead Station, Taplow, and Theale. He covered the London Midland and Scottish (LMS) Railway at Elstree, Bourne End, Northchurch Tunnel, Beattock, Berkhamstead, Tring, Watford Junction and Kings Langley. His collection focuses on Jubilee, Patriot and Royal Scot Class locomotives, together with engines from pre-grouping companies such as the London North Western Railway and the Midland Railway absorbed by the LMS in 1923. Dearden's London North Eastern Railway views show V2, A1, A2, A3 and A4 class locomotives as well as engines from constituent companies, mainly photographed at Potters Bar, Hadley Wood and Stevenage. His Southern Railway photographs concentrate on trains passing Fleet, Bramshot, Brookwood, Farnborough, Pulborough and Worplesdon and include King Arthur, Merchant Navy and Schools class locomotives.