Health firm Circle tossed back the keys to NHS hospital Hinchingbrooke yesterday less than three years after one of the most controversial privatisations ever.

Unions and campaigners said news of the failed experiment was no surprise — and vowed to continue the fight to return it to public hands.

Circle, which runs several private facilities designed to cream off “easy” cases from the national service, walked before an anticipated damning Care Quality Commission report.

Circle Chief executive Steve Melton said it had “reluctantly concluded” that its tenure at the Cambridgeshire hospital “is unsustainable.”

He blamed higher-than-expected A&E patient numbers and funding cuts for the withdrawal.

But health unions said the privateer’s exit reflected the collapse of a disastrous experiment that was destined to fail.

“We believe Circle has jumped before it was pushed with the company cynically using the A&E crisis as cover to pull out of its contract,” said Unite general secretary Len McCluskey.

Unison counterpart Dave Prentis said: “Privatising Hinchingbrooke was guaranteed to be a failure — the NHS is simply not shaped for competition.

“This government’s obsession with selling off our National Health Service is a huge waste of taxpayers’ money.

“At the first sign of trouble Circle is off, leaving local NHS patients and staff facing huge uncertainties about the future.”

The 2012 privatisation of Hinchingbrooke marked the first time ever that an entire hospital including acute services had been handed to a profiteering firm.

Until then private firms had focused on securing lucrative contracts to perform specific non-emergency operations on NHS patients.

Circle boasted that it planned to turn the hospital’s fortunes round via a £311 million cuts plan.

But experts warned at the time that the funding problems at Hinchingbrooke were caused by the competitive system imposed on the NHS.

It saw commissioners send patients to other nearby hospitals, sucking away cash from a facility saddled with debts from its construction through a private finance initiative.

Within months of the privatisation its losses had spiralled upwards.

In Cambridgeshire campaigners called an emergency public meeting to plan a response to Circle’s pullout.

Hands Off Hinchingbrooke spokesman Steve Sweeney said: “The news comes as no surprise to those of us that have long campaigned against the Circle takeover and called for them to be sacked as they lurched from one disaster to another.

“This shows that when the going gets tough, the private sector just cut their losses and walk away, leaving the already strained public sector to pick up their mess.”

The emergency meeting will be held at Huntingdon Methodist Church on Wednesday at 7pm.