The Government’s reorganisation of the NHS was its biggest “mistake”, senior Conservatives have reportedly admitted.

Labour has pledged to repeal the “toxic” 2012 Health and Social Care Act, which saw a major restructuring of how the NHS is funded. Some claim the bill was designed to pave the way for private firms to take over much of the running of the health service or even its privatisation.

Experts said the reorganisation, which is estimated to have cost about £3bn, had caused “profound and intense” damage to the NHS with one saying former Health Secretary, Andrew Lansley, would be facing disciplinary action if he had been a doctor.

A senior Cabinet minister told The Times newspaper: “We’ve made three mistakes that I regret, the first being restructuring the NHS. The rest are minor.”

One insider said the plans, which were drawn up by Mr Lansley, were “unintelligible gobbledygook” and an ally of Chancellor George Osborne said: “George kicks himself for not having spotted it and stopped it. He had the opportunity then and he didn’t take it.”

A former No 10 adviser also told The Times: “No one apart from Lansley had a clue what he was really embarking on, certainly not the Prime Minister. He [Lansley] kept saying his grand plans had the backing of the medical establishment and we trusted him. In retrospect it was a mistake.”

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Experts were scathing about the off-the-record admissions.

Mark Porter, chairman of the British Medical Association’s governing council, said: “Rather than listening to the concerns of patients, the public and frontline staff who vigorously opposed the top-down reorganisation, politicians shamefully chose to stick their head in the sand and plough on regardless.

“The damage done to the NHS has been profound and intense, so this road to Damascus moment is too little too late and will be of no comfort to patients whose care has suffered.”

Others said the bill had distracted from the need to find efficiency savings because of a looming £20bn funding gap caused by rising demand.

Chris Ham, chief executive of the respected King’s Fund think-tank, said: “You’ve got leaders in the NHS rearranging the deck chairs when we’re about to hit the iceberg.”

Clare Gerada, who was chairwoman of the Royal College of GPs until 2013, said politicians and policymakers “need to have a long, hard look at themselves”.

“They are saying this now but they should have said it then. The big issue is that nobody has been held accountable for it. If Mr Lansley was a doctor, he would have been referred to the General Medical Council,” she said.

However the Health Secretary, Jeremy Hunt, defended his predecessor.

“Andrew’s structural changes are saving the NHS more than £1bn a year. Because of that we can employ 7,000 more doctors and 3,500 more nurses,” he said.

“We wouldn’t be delivering nearly a million more operations a year or be able to put more resources on the front line without what he did.