A private equity group has snapped up Sir Richard Bran-son's online rail ticket service Trainline in a £163 million deal.

Exponent Private Equity won an auction of 12 groups bidding for the operation, which handles some 150 million rail inquiries a year.

The company, which was set up by Virgin to sell tickets online and through call centres in 1999, runs thetrainline.com, as well as operating websites for 16 of Britain's 21 rail operators and provides a business travel service for a string of blue chip clients.

Two years ago it bought rival QJump from National Express which now owns a 14 per cent stake in Trainline and is set to make £9 million from the deal. Rival Stagecoach also owns a stake of Trainline.

With a growing share of ticket sales going through Trainline, the Virgin-led ownership was under pressure from the industry and the Association of Train Operating Companies (ATOC) to sell the service to an independent operator.

The owners opened an auction while simultaneously exploring the possibility of floating the company.

The decision was taken to opt for a private equity sale but it is possible that Trainline could yet become a listed company should Exponent decide to float it in future.

Sir Richard said: "We are delighted that Trainline has gone to such a good home.

"We have nurtured the business through the dotcom boom and crash and always had confidence that it would play its part in the internet rail ticketing revolution that is now taking place.

"For some time now the rail industry and ATOC have been encouraging Virgin and the minority shareholders to divest their interests in the business through either a trade sale or flotation in order to provide it with greater independence from any individual train operator.

"The deal provides Train-line with a solid platform for further growth."