Now allocated to the Research Department D5901 is seen on the 23rd July 1974 stabled at Derby Etches Park. D5901 saw regular use on Derby's Tribometer Train and was only withdrawn due to a faulty load regulator, which was in deed fixed but to no avail. The locomotive was withdrawn in November 1975 and cut at Doncaster Works during the early part of 1977.

Railway Magazine 1972 December issue has the loco working via Wolverhampton on the 6th October 1972...