Ministers have been told to protect the vital sleeper rail service between London and the far South West from the axe amid fears the “ageing” carriages are to go.

George Eustice, MP for Camborne and Redruth, says the region’s economy would be hit if the overnight inter-city was cut under a new rail contract.

The alarm was raised after the Government published a consultation document ahead of the next Great Western rail franchise starting next year.

In it, the Department for Transport (DfT) posed questions about what services passengers wanted, and asked for opinions on the future of the “overnight service ... given that the sleeper cars and locomotives are ageing”.

Mr Eustice is concerned it is a leading question – indicating it should go – and has written to the department to say it “must be retained at all costs”.

He writes: “It is difficult to underestimate the importance of the sleeper service for those of us in Cornwall.”

MPs and passenger groups are extra protective of the “red-eye” as only a high-profile campaign saved it from the axe the last time the franchise was tendered in 2006.

The Paddington to Penzance “night riviera” service, one of only two sleepers in the UK, stops at most mainline stations in the region. Leaving the capital at 11.45pm, the train, which includes private one and two-bed compartments, arrives in Plymouth at 4.02am and Penzance at 7.53am. In the other direction, it gets into Paddington before 5.30am.

Mr Eustice, a Conservative MP, goes on: “The sleeper remains the only service that enables someone to work in London until 11pm and then get on the train and be in Cornwall in time for an 8am meeting the following day.

“It is also the only service that will get someone into London from Cornwall in time for an early morning meeting; it is difficult to see this situation changing in the next 20 years and therefore the service must be maintained.”

Last month, the Western Morning News reported that the document, out to consultation until March 31, asked whether under-used branch-line stations should be skipped to make journeys quicker.

A DfT spokesman said no decisions had been made and the purpose of the consultation was to gather views.

Mr Eustice goes on that the sleeper question “specifically refers to the age of the sleeper service carriages and locomotives”.

“Although it is true that the sleeper carriages are now a few years old, they are well maintained, perfectly comfortable and, I believe, have many years of perfectly acceptable functionality left in them.

“The locomotives themselves need either to be maintained at current levels, or, if the budget allows, replaced.”

He added: “Last time the sleeper service was under threat, there was some suggestion that the issue was not only its financial viability, but that Network Rail wanted to do engineering work overnight and found the sleeper train rather inconvenient.

“It should not, however, be beyond the wit of man to deal with that issue and park the train somewhere while engineering works take place.”

After train operator First exercised a break clause in the contract, the franchise will be put out to tender this year with the new operator taking charge of services throughout the region from next April. First has said it intends to bid.

Firms will pay the Government to run the 15-year franchise and pocket fares in return.

Last week, MPs, business leaders and passenger groups launched a campaign to lobby for more rail investment in the Westcountry.

Axeing the sleeper would be deeply unpopular. Andrew George, Liberal Democrat MP for St Ives, has written to ministers previously to say it must be protected.