Another thread http://www.firstgreatwestern.info/coffeeshop/index.php?topic=27614.msg335372#msg335372 mentioned a points failure at Taunton. From what was happening (or not), it appears that the crossover at the eastern end of the station was reversed for the 18:11 Taunton to Bristol TM^‡(resolve) to depart, and restoration to the normal position failed. Up trains were able to proceed by calling at platform 2 and using the crossover, but down trains were stuck. The first affected was 1V60 Edinburgh-Penzance that was delayed by 2 hours 10 minutes. In its rear was a light engine.

However, it appears that a common policy was followed of holding other trains at stations (on the routes from both Bristol and Westbury). So it was that westbound trains from Paddington were held at Castle Cary, Bruton, Westbury and even Pewsey.

As this was happening, 2O94, the 17:48 Bristol-Weymouth became stuck at Frome at 18:48 due to the IET^▸ (Intercity Express Train) at Bruton. Eventually it was terminated there and ran back to Westbury.

A consequence was that 2V94, the last northbound train of the day from Weymouth, was cancelled (apart from the Westbury-Bristol section).

Also affected was 2V93, the 17:53 Weymouth-Bristol, which waited at Castle Cary for over an hour.

Or any major event such as Glastonbury without other parts of the network suffering due to rolling stock and staff being needed for extra services to cope with the volume of passengers this event brings.

Which has meant the 17.28 Weymouth to Bristol has been cancelled as well.