Passengers travelling to London by train will soon have a stronger internet signal on their journey.

Customers with mobile company Three have been promised uninterrupted connectivity along the 51-mile London to Brighton route, both onboard trains and at major stations, as part of an agreement with digital infrastructure firm Cellnex UK.

Currently, mobile internet and connectivity between London and Brighton varies from strong signal to none at all due to the many tunnels and natural features along the route.

The improvements, which include constructing towers to allow the broadcasting of mobile signal, installing high-capacity fibre from London Bridge to Brighton, and bespoke radio equipment to provide uninterrupted signal, are expected to be completed later this year.

Three’s UK chief technical officer, David Hennessy, said: “At Three, our mission is to provide better connectivity every day for every customer.

“Enhancing our customer experience is at the heart of this strategy and we know how vital it is for people to stay seamlessly connected wherever they may be.

“With our 4G network now covering 99 per cent of the UK outdoor population, carrying 28 per cent of mobile data traffic, together with our partner, Cellnex UK, we are proud to lead the way in extending this to rail routes typically blighted by patchy coverage.”

Lucy McAuliffe, interim Sussex route director for Network Rail, said: “It’s great to see plans for the rollout of 5G connectivity across the route between London and the south coast.

“This will make a real difference to passenger journeys and people living alongside the railway as it will allow them to stay better connected.

“Passengers will be able to shop, work and talk whilst travelling and even have seamless connection when travelling through tunnels.”

Infrastructure director at Govia Thameslink Railway Keith Jipps said: “Network coverage along out most important rail route between London and the south coast is patchy and frustrating for our passengers.

“Getting an uninterrupted connection, even through the tunnels, will be brilliant, and the fact that the infrastructure will be 5G-ready is even better.”

The rail line serves an average of 50,000 passengers a day.