37219 runs along the up relief line at Circourt Bridge, Denchworth, on 1 December 2016 with the 1Z78 08:41 Bristol Temple Meads to Tyseley Network Rail test train. 37421 is on the rear. As has happened on a previous occasion, this was amended at short notice, starting from Temple Meads, rather than its booked 06:07 departure from Bristol High Level Siding. This also involved omitting its booked run to Severn Tunnel Junction.