Indeed, Tim. Start off small, the DOO▸ routes from Paddington to Reading/Oxford/Newbury and Reading to Gatwick along with Thames Valley branches. Then perhaps try extending to Bristol, Cardiff and maybe Plymouth.
You won’t find out what demand there is unless you try it. I don’t think it will be as large as ChrisB thinks, and it will help dampen down the horrendous scenes we often see on the 27th. Most important of all though is to wait until Crossrail and electrification works are complete so there are unlikely to be any major engineering possessions. All ties in quite nicely to include the next franchise ITT▸ if you ask me!
All makes a lot of sense to me. Do you know if Crossrail is expected to run to Reading on boxing day (not 2017, obviously)? If that is the case,
GWR▸ could even start with a simple shuttle from Reading to Cardiff VIA Bath/Bristol. A single route but it would cover Reading, Bristol, Swindon, Newport, Didcot, Cardiff, Bath which are all towards the top of the list of GWR's busiest stations and would not require any extra signalling staff to be on duty. Stations could be minimally staffed with timetable allowance made for longer train dispatches and possible engineering work.