Photos: How GNER's on-board wi-fi works

GNER's on-board wi-fi works using a combination of a satellite link and mobile 3G/GPRS networks, which enables the operator to maintain 100 per cent connectivity even when going through tunnels.

All 30 of GNER's electric trains have now been kitted out with wi-fi and work is underway on the diesels, which will be complete by the end of summer, eight months ahead of schedule. That will mean GNER is the first UK train operator to offer on-board wi-fi on its entire fleet of trains across the full route of its east coast franchise, which runs from London's King's Cross to Inverness.

Rival train operators have opted for a different approach. On the west coast line, Virgin is experimenting with a mix of wi-fi, HSDPA, non-standard WiMax and satellite technology to allow passengers to browse from their seat.

GNER has said it is also looking at the possible use of wireless broadband tech HSDPA in the future for its on-board internet access.

Rail company Southern is also testing out wireless internet technology with T-Mobile on its London to Brighton route.

Diagram credit: GNER