Double heading a Hall on the Up Capitals United Express.It's certainly unusual to have a Hall as train engine to 70015 Apollo powering through Swindon on the Paddington bound Capitals United Express the name bestowed on the 8.0 a.m. from Cardiff and the 3.55 p.m. return from February 1956 in commemoration of Cardiff formally becoming the Capital of Wales on 20 December 1955 .This might have been a way of returning the Hall back home following an earlier unbalanced working to Canton as 70015 would be more than capable of taking this working to Paddington on its own, the engine having been transferred from Old Oak to Canton in December 1956 .Further comment on this intriguing pair of photographs at Swindon, from the Locomotive Notes of the Railway Magazine, December 1957. 'On October 5th Britannia class pacific 70016 Ariel, failed with the up Capitals United Express and had to be assisted to Swindon by 2-6-2T 6155. The train was worked forward to Paddington by 1019 County of Merioneth.' So this photo shows the disgraced Britannia being towed back to Swindon shed for examination.