Just to summarise (for when we look back, 5th January)
07:33 Westbury to Swindon - cancelled (but 07:04 delayed to run in its place, so in effect 07:04 cancelled)
08:49 Swindon to Westbury due 09:42 - cancelled. "This is due to a broken down train."
Noting that the broken down train was actually off the TransWilts - it was at Bradford-on-Avon
The guard for the 07:04 Cheltenham service was stuck on the broken down Portsmouth service, hence the knock-on effect on the TransWilts.