This is an helpful update on the improvement work taking place across the Great Western this Christmas.
The GWR have a dedicated web page which sets out the affected areas and the changes this will mean to journeys.

This year there will be work at Southhall, Westbury, Guildford and Severn Tunnel Junction. The range of work means that services on the North Downs, West of England, South Wales and Bristol lines are affected, some with diversions and others with replacement buses.

GWR have recommended that customers make their Christmas getaway by Saturday 22nd as work will start from Sunday 23rd December and on many routes will continue through to the New Year.
As in previous years there will be no trains on Christmas Day or Boxing Day.