Rail passengers heading in and out of Somerset are being warned to expect four days of disruption starting tomorrow (Saturday, November 19).

RMT strike action at Network Rail's Thames Valley Signalling Centre (TVSC) on Saturday and Monday (November 21) will impact trains travelling between London Paddington and Penzance.

On those days a limited service will operate across many parts of the Western route between 7.30am and 6.30pm, with the last trains leaving much earlier.

Disruption should also be expected in the morning of the day after each strike day – Sunday (November 20) and Tuesday (November 22) – as the railway recovers from the previous days' strikes.

GWR passengers travelling from the West and South West attending the England vs New Zealand international rugby union game at Twickenham are told to not to go by train.

The TVSC at Didcot Parkway plays a critical role in the safe and reliable running of trains between London Paddington and Bristol Temple Meads, Westbury, South Wales and Cheltenham and Gloucester, meaning this strike action will particularly affect passengers in the South West, West of England, Oxfordshire, Thames Valley and the Cotswolds.

Rugby fans attending the Wales vs Georgia test match at the Principality Stadium (1pm kick off) looking to return towards Bristol and other parts of western and southern England are advised to do so immediately after the match ends.

Differently to the previous strike action, the whole of the Western route will remain open on the two strike days, albeit with limited service. Services in Devon and Cornwall, including branch lines will continue to operate to a near-normal frequency. A normal CrossCountry service will be available for most of the day but will not be able to operate at Bristol or Reading after 6.30pm.

A limited GWR service will run on the following routes between 07:30 and 18:30 unless otherwise stated:

• London Paddington and Bristol Temple Meads;
• London Paddington and Swansea: after 6.30pm trains run between Cardiff Central and Swansea only;
• London and Bristol Parkway/Cardiff;
• London Paddington and Hereford/Worcester;
• London and Plymouth: after 6.30pm trains run between Westbury and Plymouth;
• Cardiff and Portsmouth Harbour: after 6.30pm trains run between Westbury and Plymouth;
• Cardiff to Taunton/Plymouth: after 6.30pm trains run between Weston-super-Mare and Taunton/Plymouth;
• Westbury to Swindon via Melksham;
• Bristol Temple Meads to Gloucester/Worcester/Great Malvern: after 6.30pm trains will only operate to/from Gloucester;
• Between St Austell and Penzance all day;
• Devon and Cornwall branch lines to operate as normal;
• Westbury and Weymouth all day;
• London Paddington and Oxford/Didcot;
• Twyford and Henley;
• Slough and Windsor;
• Maidenhead and Marlow;
• Reading and Basingstoke;
• Reading and Redhill.

For the latest information on GWR services including ticket acceptance and how to claim a refund, click here.

Network Rail's interim Western route director, David Davidson, said: "I'd like to sincerely apologise to passengers for this latest disruption.

"It's really disappointing that the RMT has decided to call this needless strike action which will severely impact passengers over a four-day period, starting this Saturday 19 November.

"This strike action will have a significant impact on passengers travelling from the South West and West to watch the England vs New Zealand rugby match at Twickenham. There will be no train services travelling West after the game, so we are asking those passengers not to travel by train.

"We have been working closely with the train operators to agree the services they will be able to operate during this time but please continue to check with your train operator on the services they are running or visit the National Rail Enquiries website for more information."