Brighton passengers travelling to and from London will have to add an extra 40 minutes onto their journey while works take place.

Some 1,500 metres of track will be lifted over next weekend as improvements are made on the Brighton Mainline between Gatwick Airport and Purley.

The works mean that no direct trains will run between Gatwick and London with services being diverted through Horsham - adding almost an hour onto the trip.

Lucy McAuliffe, Network Rail’s Sussex route director, said: "We’re really pleased to see further investment being made in improving the reliability of the Brighton Main Line, a key commuter route that needs constant work to keep it running.

"We’ll be taking all lines out of use between Gatwick and Purley to tackle a host of maintenance work, including renewing track at a major railway junction near Coulsdon."

Southern, Thameslink and Gatwick Express trains will be affected by the works on January 20 and 21.

The Argus: Network Rail engineersNetwork Rail engineers

The sleepers, ballast and three sets of points will be replaced and refurbished, which engineers at Network Rail hope will make the journeys of 17 million passengers smoother and more reliable.

Gatwick fliers have been told to allow plenty of time to travel before their flight.

Jenny Saunders, customer services director for Southern and Thameslink, added: “While we’ve arranged alternatives to help our customers get where they need to be, several routes are affected and many journeys will take considerably longer than normal.

A direct service will run between London Victoria and Gatwick Airport via Horsham, calling at Clapham Junction, Horsham and Three Bridges.

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Journeys between London Victoria and Gatwick Airport will take around 80 minutes instead of the usual 30 to 40.

Trains that usually run between Littlehampton and London, and between Eastbourne,  Hastings, Ore and London, will start and terminate at Three Bridges.

A limited service will run between Brighton and Three Bridges, and between Horsham and Gatwick Airport.

Buses will also replace trains between East Grinstead and Gatwick Airport, East Grinstead and Three Bridges and Gatwick Airport and Redhill.

A spokesman for Network Rail said: "Passengers planning to use replacement buses are advised that because of a national shortage of bus drivers, they should check before they travel and may experience delays."