The health service should not expect a “sudden overnight change on 1 April next year” to an autonomous and liberated system, the chair of the NHS Commissioning Board has told HSJ.

Malcolm Grant made the comments in his first interview since taking up the post at the independent board six months ago.

Professor Grant said the board had to create a “transformatively different” reformed service at the same time as meeting the “challenge of trying to bring £20bn cost reductions through the NHS” and maintaining performance.

He said: “Running two systems in parallel is very risky. We don’t want to lose any momentum on QIPP [the NHS’s quality, innovation, productivity and prevention programme] or any of the achievements of the present system while we bring in the new. [The change] will not be overnight, it is not that suddenly the lights are going to go off on 1 April and a whole new sunlight will be turned on. It’s going to be a long process of really hard work.”

The board’s chief executive Sir David Nicholson has taken a rigorously controlled top-down approach to management of the service – which he has described as “grip” – during the transition.

Professor Grant said he believed that was appropriate because of the need to make huge efficiency savings.

However, he claimed this “grip” would have to loosen and the ability of leaders transferring from the current system to change their “behaviour” was a “fundamental question” for the new NHS.

He said: “We have a lot of the same people but it doesn’t necessarily follow they [will] behave in the same way. You cannot behave in the same way. The model is no longer capable of being one of top-down

Professor Grant – who is still also provost of University College London – said: “If [the new system] is not different and transformatively different then we are wasting our time.”

But he said: “It will not be a sudden overnight change on 1 April next year… We are dealing with human beings and human beings have habits. The critical thing will be leadership and ensuring we have got the best team nationally, and also the strongest teams in our regional and local offices.”

HSJ’s interview was conducted after the health secretary declared his first “priorities” for the board in a letter sent to Professor Grant on Friday. Andrew Lansley said its “overarching objective” was that it “transfers power to local organisations”.

The letter said the board should follow a philosophy of “assumed liberty” for CCGs, as opposed to “earned autonomy”.

Responding to this, Professor Grant told HSJ: “We make the assumption of liberty but of course we have a responsibility to provide a comprehensive health service, and for that we do have powers of intervention.”

Another instruction in the letter was that the board should “maximise the number [of CCGs] that can be authorised fully, without conditions, by April 2013”.

The commissioning board has previously indicated requirements may be asked of many CCGs when they are authorised. These could include withholding part of their budget, telling them to employ specific managers for support, or requiring them to improve plans for a particular area.

Professor Grant told HSJ that although many emerging CCGs were already “hugely impressive”. He added that “in some parts of the country things are still some distance from that point”.

He said he would “be disappointed” if the proportion of CCGs authorised was not “very close to 100 per cent”.

However, in relation to authorisation conditions, he said: “Conditions will be variable. There may be some who are authorised with relatively marginal conditions and some who may need to be authorised with rather more intrusive conditions.”