Further advice just received ... with a proviso form me.
Trains may be thin on Sunday, but if you wait to Monday there will be no trains at all ... Pewsey, Bedwyn, Hungerford and Kintbury passengers beware!
GWR▸ is advising customers planning to travel on long distance intercity services on Sunday 15 July that a revised timetable will be in place with a significantly reduced number of trains in operation. Long-distance services – including routes between Paddington and Bristol, South Wales, Oxford and Devon and Cornwall will be most affected, with some changes to suburban services in the West. Trains that do run will be extremely busy.
Local stopping services in the Thames Valley are expected to run as normal.
Passengers are advised to travel as early as possible, and to consider switching their travel plans to alternate days. To help with this, ticket restrictions have been removed from services on Saturday 14 and Monday 16 July, so that customers with tickets for Sunday, including Advance fixed train tickets can travel on other services. Ticket acceptance has also been agreed with CrossCountry trains.