37254 runs along the up relief line at Circourt Bridge, Denchworth, on 23 February 2017 with the 1Z23 07:14 Bristol High Level Siding to Tyseley Network Rail test train. 37421 is on the rear. This is just a split second away from being a completely dull picture. In this case the shadows were moving much faster than the loco, possibly ten times faster! The train was travelling very slowly, as it was right up behind 43174, which had only just moved off from the next signal. However, the shadows were zipping along, as the gale force winds were moving the clouds at very high speed. As an example, there was no sign of this approaching cloud, even when 37254 was in the position that 37421 is at in this picture!