The unit was taken on by the Railway Technical Centre at Derby in 1967. The cars were renumbered RDB 975003/4, and the set became Laboratory Vehicle 16. It later acquired the name Gemini, in the Centre's cryptic style, and the Departmental red/blue livery. It was used for "BRATO", -British Rail Automatic Train Operation tests, using track/train-mounted equipment. It was usually based at Mickleover and operated on the Mickleover - Eggington Junction test line, until declared redundant early in 1984 and put up for sale.