Picture: Phil Crosby. 'Lido' at Middleton-in -Teesdale Station.
Following completion of Heavy and General Repairs, Locomotives were given trial runs, with Works inspectors,before release from Main Works and return to traffic.
This was certainly the case with Darlington North Road Locomotive Works which continued work on Steam Engines until closure in 1965/6.
Freight Locomotives were trialled on the Darlington to Middleton-in Teesdale line, Main Line Passenger Locomotives had a much longer trial, going from Darlington round by Bishop Auckland before joining the East Coast Main line just south of Durham, then to Newcastle before returning on the coast line through Sunderland and Hartlepool.