Duncan Selbie, who piloted the introduction of the 18-week maximum wait target, is to leave the Department of Health before the target is due to be hit.

The DoH director general for commissioning is set to take up a chief executive post at an unnamed trust on secondment this summer, with the 18-week target not due for delivery until the end of next year.

Mr Selbie joined the DoH in 2003 as director of programmes and performance and during his time at Richmond House has been responsible for implementing many policy changes, even lending his name to the 'Selbie six', the six key local priority performance targets for organisations to deliver in 2006-07.

NHS Confederation chief executive Dr Gill Morgan said Mr Selbie wanted to expand his CV having been with the DoH for four years. He has worked in every part of the NHS apart from the acute sector.

She said: 'He's been talking for some time of the breadth of his experience so it seems a perfectly rational move.'

But, she added, 'the whole purpose of a secondment is to give someone choice', so it was possible Mr Selbie will return to the. DoH. 'It will depend on whether he enjoys the cut and thrust of the acute sector,' she said.

NHS chief executive David Nicholson said Mr Selbie had done 'an outstanding job', since he joined the DoH.

'In his time we have met the most challenging targets the NHS has ever been asked to achieve, got the NHS back into financial balance and produced a set of plans for next year that will improve patient care.'

Before he moved to the DoH, Mr Selbie was chief executive of South East London strategic health authority and before that chief executive at South West London and St George's Mental Health trust.

He said: 'It has been a privilege to have led delivery and the implementation of reform across the NHS. After four years in Whitehall I'm keen to refresh my frontline experience and really looking forward to being a hospital chief executive.'

The DoH said it would announce plans to replace Mr Selbie 'in due course'.