THE prestigious Caledonian Sleeper train is in danger of going to the dogs, a rail union warned yesterday after the notorious privateer set to take it over plunged into loss.

Contractor Serco — which soaks up wads of taxpayers’ cash in lucrative contracts across the public sector — panicked its investors earlier this week as its share value tumbled.

Newly released figures show it plunged from profits of over £100 million to a £7.3 million loss in the first half this year.

It was hit by a ban on further government contracts last summer after it ripped off taxpayers by charging for tagging non-existent criminals.

But in May, just after it emerged from the ban, it was announced that Serco would operate a revamped sleeping car service between London and Scotland.

Rail union RMT has written to Scottish transport minister Keith Brown urging him to reconsider awarding Serco the franchise.

“It would be a massive gamble for the Scottish Parliament to plough on regardless of the hard facts,” he said.

“This would leave the important and iconic Caledonian Sleeper at clear risk of collapsing into the kind of chaos that seems to trail behind Serco like a bad smell.”

A Transport Scotland spokeswoman said: “The Scottish government is obliged, under Westminster’s franchising legislation, to award the franchise contract to the best bid.

“Serco continues to pass the necessary financial tests for this contract.”