The up platform at Bradford-on-Avon was controlled by a sole colour light (BJ102). This was, in fact, a very distant-distant from Bradford Junction signal box some three miles away. If a through train was due, BJ102 would show green and remain so for some length of time prior to the arrival of the train. I believe that the green was given after the train had passed over Bathampton Junction but I could be wrong? Us spotters would all get very excited if this happened as it heralded the arrival of something unusual. Our eyes would be peeled looking up the one mile or so of straight track west of Bradford-on-Avon in anticipation of what was coming! On this particular morning, this event heralded the passing of an up diversion to London Paddington headed by 50027. I had to go for these more head-on shots to avoid the plague of motion blur as the Exa camera had a maximum shutter speed of 1/150 sec. However, my timing was not always spot-on as demonstrated by the shadow cast by the footbridge! In recent years, rampant tree growth has altered this viewpoint considerably, see.....
https://www.ontheupfast.com/p/21936chg/29201867204/x150238-13-10-weymouth-gloucester