Justifying the billions of extra cash pumped into the NHS is the biggest challenge the service faces, a former health adviser to Tony Blair claimed last night.

Simon Stevens said it was up to individual hospitals and their trusts to prove they were improving.

Speaking to The Birmingham Post ahead of a talk in the city, Mr Stevens said annual finding to the NHS was growing from #35 billion in 1997 to a predicted #92 billion by 2008. "The question is whether the NHS is evolving fast enough compared to the money going in.

"The bulk of the extra money has gone into employing more staff in uniforms. Yes, a significant part of it has gone on paying NHS staff better.

"But if you want well-motivated doctors, nurses and therapists, then the NHS has to keep up with the kind of rates of pay across the rest of the sector.

"What has tended to happen is that the NHS has gone through a period where pay has fallen behind and then you go through a rapid catch-up."

Mr Stevens, who now works in the private sector, added: "The big issue now is how to get new ways of working the system so you have services that are more responsive from the patients' point of view and where you are improving the quality of health care."

Birmingham-born Mr Stevens was an adviser to Mr Blair for seven years. He applauded the current Government for trying to address the funding crisis within the NHS.

"For maybe 20 or 30 years, because the NHS was pretty efficient, we kidded ourselves we could have an NHS on the cheap," he said. "It wasn't until the year 2000 that there was an honest debate with the public, saying if you want to have a well-funded NHS you have to pay for it."

Despite recent bad publicity over job cuts, Mr Stevens said the service was still employing "hundreds of thousands" more frontline professionals than five years ago.

And he defended controversial PFI projects such as the #589 million University Hospital Birmingham scheme, claiming the important thing was the city was getting a new hospital.

Mr Stevens, who delivered a speech to health professionals at Birmingham's Council House, said good managers made all the difference to delivery and staff morale.

"There are not enough of them at the moment," he said. "One way is to have doctors and nurses involved in the running of the hospital and there has been a move to do that."

The health expert said it was "obvious" the current Government was committed to the survival of the NHS.

But he added its future lay in the hands of managers and their ability to listen to what patients are saying they want from the service.