There was one last week as well. It seems to be a consequence of two track railway. The 387s go to Swindon (or Bristol Parkway) instead of Didcot to relieve possible overcrowding on the 80x services, with Didcot to Reading shuttles serving the local stops in between.
I'm wondering whether, instead of the current Didcot to Paddington stopper, whether it would be more beneficial to have extra Paddington to Swindon 387s and then just have the Didcot stoppers as far as Reading (waiting for Tilehurst and Goring passengers to kick me in the b*llox for suggesting the removal of their direct Paddington services

).
However, although this may be best for a separate thread, I'd like to see an hourly Swindon to Gloucester Turbo, even if just a 2 car 165, to plug in the hourly gap down the Stroud Valley (xx:45 from Gloucester and circa on the hour from Swindon). That 1750 Gloucester to Salisbury via Swindon and Melksham is actually very well loaded as far as Swindon in fairness.