I was at Salisbury station yesterday, just after 18.30. I noticed that the train to Cheltenham Spa (orig. Southampton) via Melksham and Swindon had already been reported as cancelled.
The reason on the screen: "shortage of coaches"
I have photographic evidence. I will post later.
I suspect you have been Glastonburied.
I had suspected so too ... but I've just received the following from FGW.
Unfortunately, due to Diver sickness, we had no option but to start the 18:27 Southampton service and terminate the 1728 Cheltenham service at Swindon on 20 June. We will always look to cover any ongoing staffing problems, but there are occasions when this is not possible and I am sorry for the inconvenienced caused.
So the driver of the southbound was sick and the train had to terminate at Swindon at 18:35. But we know that the Gloucester crew work down to Westbury and back before going up the Stroud Valley again. So that two hours he had in Swindon game him time to recover and resume duties from about 20:20.
I'm not sure how the "coach shortage" fits in to this story ... unless the story we've heard is incomplete, or parts of it are wrong.
I do know the line was very busy these last two evenings with "Glastonbury Specials" - Lisa was waiting for me on the platform at Melksham last night for the 19:08 arrival and reported 3 (!) passenger trains through while she was there.