I was caught up in this. I had planned on catching the 1736 from Swindon to Westbury (I'd've done a count grahame
).
It became apparent fairly quickly after I arrived at Swindon Station at 1715 that nothing was going to head to Chippenham. The 1657 to Bristol Temple Meads (1600 from Paddington) was being held at the station and while I pondered what to do, whilst stood near the Customer Service desk on the up side, I overheard a radio message that said the 1657 was going to Bristol
TM‡ via Bristol Parkway.
I decided to bin the idea of going to Westbury (then home later) and head home to Bristol instead.
The following down service to Taunton (1630 from Paddington) was also diverted via Bristol Parkway and dispite being held up outside Swindon was only running 10 minutes late after its diversion.
At Swindon, Bath Spa bound passengers were being advised to travel on the diverted services to Bristol TM and pick up connections there. Chippenham passengers were the real losers (as well as those for Melksham of course!) - it was hanging around for replacement road transport for them.
There were, from what I can gather, numerous small lineside fires. Could a passing freight train have been the culprit (hot box?). There was one in the area at the time. There was also mention that one of the fire locations was near to a traveller camp beside the railway.
That's what I've gleaned from various sources and I'm not pointing the finger or speculating further.