Built at Swindon Works under Lot No. 278 in December 1932, Diagram A10 Class 61xx 'Large Prairie' No. 6145 entered traffic at Old Oak Common, employed on London suburban services, even over London Underground metals. Class 61xx locomotives were the mainstays of the Thames Valley suburban services until replaced by DMUs, illustrated by 6145's allocations to Old Oak Common, Slough and Oxford sheds.