THE Caledonian Sleeper has enjoyed a resurgence in popularity in the last half-decade as more people opt for the UK's only remaining overnight passenger train over short-haul flights.

Figures seen by The Herald show there were 274,000 passengers carried between London and Scotland in the 2010/11 financial year, a 31% increase on five years earlier.

The upturn has been welcomed by rail enthusiasts, who have hailed the service as the last vestige of a more romantic era of rail travel, and comes after the Department for Transport and Scottish Government agreed last month to provide £100 million between them to ensure the service continues.

However, the figures, which were passed to The Herald by Government agency Transport Scotland after a Freedom of Information request, show the cost of operating the service is significant, with subsidy levels of at least £76 per passenger.

Sleeper trains were commonplace in the 1920s and 1930s but dwindled after the Second World War as they faced competition from motorway travel and, more recently, short-haul flights.

The Caledonian Sleeper, saved from the axe during privatisation in the 1990s following a public campaign supported by many Scots MPs, faced more uncertainty last year.

A Scottish Government consultation had proposed cost-saving measures such as removing either the "lowland" service to Edinburgh and Glasgow or the "Highland" service to Fort William, Inverness and Aberdeen.

Transport Minister Keith Brown said it had always been the intention of ministers to fund the sleeper service beyond 2014 and make improvements.

He said: "These figures show the clear demand for the Caledonian Sleeper and that we have been right to retain our commitment to the service.

"I was delighted to recently announce we have submitted proposals to the Treasury that will see us invest, as a minimum, £50 million to ensure the Caledonian sleepers are enhanced to offer better facilities and a more responsive service to passenger needs.

"We are now in discussions to work out the finer detail of exactly what those enhancements will be."

The service received a significant fillip in 2010 as flights were cancelled en masse due to volcanic ash drifting over European airspace from Iceland, according to passenger figures.

However, the figures also show there has been a steady upward trend in passenger numbers which dates back to 2005.

Mark Smith, a rail enthusiast and author of the respected Man in Seat 61 guide to UK train travel, welcomed the figures.

He said: "Over the last five to 10 years people have fallen out of love with budget airlines and are getting fed up with the hidden charges and hassle of security checks.

"There was a big increase in sail/rail tickets to Ireland during the ash cloud disruption but what we discovered was the growth was sustained after flights returned to normal. I suspect it is the same with the Caledonian Sleeper.

"Personally, I love it. It's a practical, convenient way of getting from central London to almost anywhere in Scotland and great fun."

The figures were also welcomed by First ScotRail, which has operated the Sleeper since winning the passenger franchise in 2004.

A spokesman said: "There is no doubt that the airline disruption caused by the volcanic ash cloud had a positive impact on the Caledonian Sleepers. There have been high levels of retention since, with the services showing strong performance.

"We continue to promote the benefits of Sleeper travel, including that it saves time with no lengthy transfers as it is from city centre to city centre and gives travellers more time at home or in the office."