The health secretary has said the NHS is “on track” to make the efficiency savings required over the next four years.

Andrew Lansley was speaking at a question and answer session hosted by the Smith Institute, Asthma UK and the Association of Chartered Certified Accountants on Tuesday.

He said more than half of NHS organisations were currently expecting to meet their savings plans during 2011-12. Mr Lansley also said spending in 2010-11 had been lower than expected.

He said some savings under the quality, innovation, productivity and prevention (QIPP) efficiency programme were “back end loaded” – with more intended to be achieved between 2012 and 2014 than in 2011-12. The DH has said the NHS must make £15-20bn efficiency savings by 2014-15.

Mr Lansley said: “The 20 per cent of QIPP [which is] about redesign of services is designed to be achieved in future years… [it] is back end loaded.

“The QIPP [information] I have seen suggests we are still on track to make that happen over four years.”

However Milton Keynes Hospitals Foundation Trust interim chief executive Mark Millar, an ACCA council member also speaking at the event, disagreed.

He said savings were not being made quickly enough in hospitals – in which funding through the tariff is being reduced steeply – or through service redesign and reconfiguration.

He said: I think we’re behind… I am not as convinced as the secretary of state that at our current rate we will get the [savings] from tariff and from redesign in the timescale that we need it.”

Mr Millar said those planning services generally knew what changes needed to be made, but they could not implement them due to “vested interests”.

He said: “We are behind particularly because of vested interests. The gap between [having] a beautiful plan and implementing it, with lots of vested interests, is difficult. We need to address the real barriers on the ground.”

Mr Lansley was also asked – by Liberal Democrat activist and former deputy chief medical officer Graham Winyard – why few doctors supported his plans.

The health secretary admitted enthusiasm among GPs for commissioning had been damaged by the uncertainty and controversy around his plans.

He said: “My experience was at the outset they were pretty enthusiastic. I expect enthusiasm has been mitigated somewhat by listening to a debate [about the reforms].”

Mr Lansley said GPs “worry” his plan to put them in charge of commissioning will fail because they have seen previous attempts at clinical commissioning such as GP fundholding fail.

He said: “Understandably they worry that this is just another Duke of York [situation] – that they might be marched up to the top of the hill and back down again – I’m determined that will not be the case.”

Mr Lansley said opposition to the decentralisation in his reforms was also due to “vested interests”.

Of his plans to localise control with clinicians, he said: “The intensity of debate about the bill is right – [because] nobody has ever done this before.

“The people who are trying to push it back to the centre are the people who are likely to have a vested interest… Clinically led decision making is a threat to organisations that like to have all the decisions made at the centre because they think that is the best way of influencing it.”

Citing Machiavelli’s book The Prince, Mr Lansley said radical change was often strongly resisted in favour of the status quo, and he was right to introduce change quickly over the past year to ensure it happened.

He said: “You have to do it quickly. If you wait around it will never happen. The lesson of the last year is it has to be done quickly – yes with a clear vision, [and] you have to be prepared to listen and take people with you.”