Virgin services will not be running from London's Euston Station

Services in London, the West Country and on the Midland, East and West Coast Mainlines have been affected.

Rail operators have warned passengers to expect extended journey times and replacement bus services on Sunday.

Meanwhile, traffic conditions are "fairly good" for an Easter holiday weekend, with most travellers already at their destinations, the AA has said.

Essential improvements

George Muir, director general of the Association of Train Operating Companies, acknowledged that the Easter period was a busy time of the year.

"It is also a time when major engineering works are best carried out to take advantage of the four-day break," he said.

"These essential improvements will increase performance and help trains to run more smoothly and on time."

Diversions will be in place in the West Midlands area, adding an extra hour to journeys between London and Manchester

In London, work on the Channel Tunnel has led to the closure of St Pancras station with Midland Mainline services departing and arriving at Luton.

Two of the four main lines out of Paddington have been closed with Thames Trains operating a reduced service.

Until Tuesday lines into Waterloo station will be affected, with journeys to Southampton, Portsmouth and Salisbury disrupted. Victoria station services will also be disrupted.

Buses will replace the Stansted Express service on Sunday as part of an ongoing programme of signalling work.

Not stopping

In the West, the Severn Tunnel will be closed, services between London and South Wales will be diverted via Gloucester and the route between Taunton and Exeter will be closed on Sunday.

Engineering crews will be working on Sunday

Virgin services on the West Coast Mainline have been disrupted, with no trains leaving Euston, coach services in place between Northampton and Hemel Hempstead, and a Silverlink service to and from Euston.

Diversions will be in place on Tuesday in the West Midlands area, adding an extra hour to journeys between London and Manchester.

On the East Coast Mainline GNER services will not stop at Wakefield.

In north Wales, flood damage has caused the cancellation of Arriva Trains services between Llandudno Junction and Blaenau Ffestiniog, with a bus replacement service now running between the two stations.

More that two million Britons have taken to the air, flying abroad to New York, Dublin and Amsterdam.

Sunseekers have also booked up nearly all tickets to the Canary Islands, mainland Spain, the Balearic Islands, Cyprus and Turkey.

Florida has also proved popular with families because of the continuing strong value of the pound against the dollar.