A Dean Forest Railway Preservation Society chartered excursion on 6th October 1973 which travelled from Cardiff via Newport, Severn Tunnel Junction, Bristol Parkway and Gloucester, to Long Marston, Quainton and Didcot. The formation comprised 3-car set No. 502 (DMSL W50693, TSLRB W59299 and DMBC W50738).

References:
Dean Forester Comes to Quainton - Reg and Janice Uphill - Quainton News No. 18 - December 1973