Peter Kerslake says "Climbing to Patchway from the Severn Tunnel 4086 Builth Castle is making heavy weather of the gradient and losing a substantial amount of steam from its cylinders heading the Paddington bound "Red Dragon" express from Cardiff.
After arrival at Paddington it will be turned, watered and oiled at the adjacent Ranelagh yard before working back home to Cardiff later the same day. This was the normal practice for locomotives coming up from South Wales.
A Laira engine in the ' fifties 4086 was transferred firstly to Swindon in 1957, then moved to Reading but at the date of this view was shedded at Cardiff Canton before a final move back to Reading in May1961 from where it was condemned in April 1962."