NHS campaigner and author John Lister asked Lord Darzi to give one example of the private sector delivering high-quality healthcare yesterday after the former health minister criticised Labour policy.

Lord Darzi became the latest high-profile Labour figure to speak out against party proposals to curb private-sector involvement in the NHS.

The peer told Newsnight that high-quality care is more important than whether it is delivered by the public or private sector.

His comments follow those of former health secretary Alan Milburn, who claimed that reversing the sell-off of the NHS would be a “fatal mistake” and could cost Labour leader Ed Miliband the general election.

But Mr Lister said there is no proof that the private sector provides decent care, but instead plenty of evidence of its failings.

The Health Emergency campaign director highlighted how Tory ministers trumpeted Circle for becoming the first private company to run an NHS hospital — Hinchingbrooke in Cambridgeshire.

But after just three years Circle was forced to pull out of the contract, leaving the hospital “£7 million in the red and sinking.”

Mr Lister added that quality goes out the window when profits take priority.