This version of the ‘Salmon’ bogie rail wagon represents the ‘YMO’ in conventional form with five bolsters for carrying 60ft lengths of rail. It is in the earlier black departmental livery.
History
The ‘Salmon’ bogie rail wagon was based on an LMS design. Measuring 62ft-long and fitted with five bolsters, they were made in large numbers during BR’s early years, with 849 built between 1949 and 1961. Almost 400 remained in service as late as 2008, by which time they had been upgraded with air brakes and new bogies. 
A single wagon could carry a number of 60ft rail lengths, or a rake of wagons could handle 600ft lengths of welded rail. Originally painted black, they were later painted yellow and saw widespread use as departmental vehicles used by the railway’s permanent way and civil engineering departments.