English Electric Type 3 No. D6857 heads towards Cardiff with an up steel billet train on the GW main line near St.Fagans on 7th August 1965.
The wagons are British Railways built Dia. 1/411 45 ton 'Slab/Coil' wagons - written 'SLABCOIL', of which 58 were built at Swindon in 1962 to Lot 3424. Under TOPS they became 'JZV' and were built for carrying slab or rolls from Margam steelworks, and were branded "Return to Margam" and are probably heading for the then Spencer Works (Llanwern). The load capacity of 1/411 was 45T and the Tare 29T, so maximum weight 74T per wagon, plus 20T for the brake, giving a total of just under 1,000 tons for a 13 wagon train, assuming all wagons are carrying the maximum - quite a load for a single class 37. Double heading being very unusual in 1965.

Photo: R.O. Tuck/Rail Archive Stephenson