Hornby R40009 BR R&D Division Ex-Mk1 BSO Laboratory 10 RDB 975428.
RDB975428 Laboratory 10 was designed by BREL and is depicted here in its 1979 RTC Red livery. It was the former Mk.1 BSO, M9236, converted for use by the research & development division of British Rail at Derby RTC and used as a generator car for the APT testing POP Train.
It is 265mm (length).