The House of Lords has failed to make significant changes to the Health Bill, the influential crossbencher Lord Owen has said, calling on the prime minister to scrap the legislation before it becomes law.

In an essay published today Lord Owen says the bill remains “fatally flawed” – the phrase he used to describe the bill at the beginning of its passage through Parliament last March.

In it, Lord Owen says: “It is crystal clear that despite the best efforts of all those concerned and despite the many amendments that will be passed, the fundamental structure will remain intact.”

This is despite outspoken opposition in recent weeks from a growing number of royal medical colleges.

Lord Owen also accuses the coalition government of breaking parliamentary convention by going ahead and implementing many reforms before the bill receives royal assent.

The only way the reforms can be halted now is if prime minister David Cameron decides to scrap the legislation, he said.

The essay says: “Of course, halting the Health and Social Care Bill will be a political rebuff, a U-turn over which the Labour Party would be bound to crow for a while. 

“But the prime minister showed over the government’s forestry proposals that that sort of criticism lasts for a few days and is soon forgotten.  The prize for foregoing the Health and Social Care Bill is potentially immense.”

Lord Owen told HSJ the bill was “absurd” and “impossible to amend” unless the underlying thrust of it was changed. Lords had succeeded in making “marginal improvements” but, “we cannot pretend we’ve dented this bill in any significant way”.

He added: “I don’t think the bill will get held up by anything we do in the House of Lords.”

He predicted that amendments to the Secretary of State’s powers are likely to be agreed, meaning that “a secretary of state who wants to be involved can be”. However significant changes to the bill’s section three, primarily about competition were unlikely, as was a large-scale Liberal Democrat rebellion.

“Andrew Lansley knows what he wants – he doesn’t shift his ground. He makes tactical retreats, little amendments – but we shouldn’t delude ourselves – the commercialisation and marketisation will proceed.”

A Department of Health spokesman said: “Following the unprecedented listening exercise, where we heard from thousands of people, we improved the bill substantially. And following discussions in the Lords, we made further significant improvements to clarify that this bill is about handing power to clinicians and putting patients at the heart of the health system.”