A continued existence beyond 2013 for primary care trust clusters looked increasingly likely this week, as the health secretary’s NHS reforms came under huge political pressure.

Andrew Lansley accepted there would be “substantive” changes to his Health Bill, following a threat from deputy prime minister Nick Clegg to veto it.

The changes are still the subject of negotiation and unlikely to be known until at least the end of this month - when the government’s “NHS Future Forum” formal review of the plans will report.

However, HSJ understands that Liberal Democrats leading negotiators are pressing for PCT clusters to be retained and for consortium commissioning to be made optional.

One of those involved told HSJ the clusters - possibly renamed “local health boards” - would be the commissioner where consortia did not exist.

“Enthusiast” GP groups taking on commissioning would be performance managed by their cluster. Clusters would keep some duties - such as commissioning primary care - which under Mr Lansley’s plan would pass to the national NHS Commissioning Board.

The source said: “If enthusiasts want to proceed and they hit the threshold of quality and governance then [we would] allow them to proceed.

“You learn lessons from that, you build up an evidence base for what works and what doesn’t but you don’t impose the same model across the whole country by conscription from the centre.

“The history of the NHS is littered with major structural reorganisations which failed to live up to the promise that was made at the start. A more evolutionary approach makes sense.”

The view contrasts with Mr Lansley’s proposals to abolish PCTs altogether in April 2013.

Meanwhile a senior health service source confirmed national and regional managers were considering alternative “scenarios”. A favoured option would make clusters statutory organisations which, if GPs agree, can establish consortia as sub-committees and delegate commissioning. The source said it was likely to be thought “too expensive” for clusters and consortia to be separate statutory bodies.

Another scenario is for clusters to be retained as outposts of the NHS Commissioning Board, without their own boards. Where GPs choose, consortia could be established as statutory bodies.

The source said leaders were also examining what reforms would help make the huge efficiency savings required. The source said: “A lot of these reforms don’t answer the questions we need answered [in order to make the savings].”

In a move that could lead towards similar arrangements, Cambridgeshire has already formed an organisation of GPs above consortium level to promote clinical involvement in commissioning during the transition to GP consortia.

Senate chair Dr Simon Hambling said: “Officially it will wind down when the PCT does. Whether there is an inherited organisation remains to be seen.”