... the 17 06 from Paddington to Twyford (well it goes on somewhere else but never gone any further) seems to have become a 3 car turbo as opposed to the Intercity 125 it use to be. ...
It's the Bristol via Trowbridge service, and due to current route restrictions cannot be a turbo all the way. This service (the only through train of the day from Paddington to the county town of Wiltshire) looks set to be lost post-electification though most of the passengers, Sixty3Closure, seem to use it for the same part of the journey that you do and traffic beyond the Kennet Valley is sparse. Perhaps part of that sparseness is explained by the early (05:48) departure of the opposite working from Trowbridge into London which must be one of the earliest "last through train" departures anywhere in the country!