37421 passes Chilson in superb light on 1 December 2016 with the 1Z78 08:41 Bristol Temple Meads to Tyseley Network Rail test train. 37219 is the rear locomotive. One or other of the locos (37219 I think) was making a slightly odd noise, with the engine apparently 'hunting' up and down the rev range. Obviously it wasn't anything serious, as the train completed its journey successfully.