For all of the miscalculations and cock-ups of the past two-and-a-half years, the Tory party, and David Cameron in particular, are as strategically focused as ever on winning power and holding on to it.

Few will be surprised to learn, then, that Cameron is still determined to force through parliamentary boundary changes next year that will reduce both the number of seats in parliament and in particular the number of Labour MPs, (by about 30) – and all in the face of opposition from Nick Clegg. And despite Clegg's protestation, the Tories will probably be able to buy off some Liberal Democrat MPs threatened with extinction with a place in the Lords or on a quango. That he appears to be promising more devolved powers to Northern Ireland and Wales in order to win over the unionists and Plaid Cymru is quite logical in the circumstances.

In Wales, the carrot for Plaid Cymru is more assembly members in return for fewer, mostly Labour, MPs in Westminster. But it is what may be happening behind the scenes between the Tories and the Scottish Nationalists that could prove to be the real deal-maker (and the deal-breaker with Clegg). It could also be effectively reshaping the United Kingdom, and without any public debate. With unionist and nationalist backing in Northern Ireland, Scotland and Wales – and heavy whipping of the 40 or so Tories with considerable concerns about the shape of the new parliamentary boundaries – Cameron could yet out-vote both Labour and the Lib Dems. In return, the Conservatives and the Scottish Nationalists could between them, refashion the union.

Driving what appears to be an emerging concordat between David Cameron and the SNP leader, Alex Salmond, is a belief that both sides stand to gain quite substantially from agreement over boundary changes in return for a "devolution max" that stops just short of full independence for Scotland. According to former Conservative MEP John Stevens, Cameron could announce shortly after the European elections in 2014 that the Scottish referendum would be a choice between "devo max" and full independence.

So what is devo max? As yet, no leading political figure has really attempted to define it. But, says Stevens, the devo max Cameron has in mind involves Scotland "no longer returning MPs to Westminster". Joint jurisdiction over defence and foreign affairs could be decided by ministers from both parliaments or representative Scottish MSPs coming to Westminster only when key defence or foreign affairs votes need to take place. "The advantage for Cameron in this scenario," says Stevens, "is that he can claim to have both saved the union and finally answered Tam Dalyell's infamous West Lothian question". The even bigger advantage is that through a combination of advantageous boundary changes and a removal of the Scottish Labour block, the Tories would hold sway in virtual perpetuity.

The government's commitment to set up a West Lothian commission gives credence to the discussions that Stevens says are going on behind the scenes. In January, the then leader of the House, Sir George Young, said the commission would look at a range of options such as only English and Welsh MPs voting on issues that affect only England and Wales. Young said: "In my view, that would be an appropriate rebalancing of the constitution to take account of the fact that in Scotland, they have their own parliament in which issues are resolved on which English MPs cannot vote. It seems somewhat perverse that Scottish MPs can vote on those very same issues when they apply only to England."

That "perversity" is what is driving some in the Tory party, who are described by some vexed colleagues as "south English separatists", to push for the creation of a standalone English parliament. Some of these so-called Tory separatists were behind demands for the West Lothian commission. They have little interest in Scotland remaining as part of the union and are often from the Eurosceptic wing of the party.

For those who find it difficult to imagine that David Cameron or Alex Salmond have much in common, still less could collude, recent memories of the once staunch enemies, Ian Paisley and Martin McGuinness, as the re-christened "Chuckle brothers", is enough in itself to persuade many that some deeply serious brokering is not only possible, but is under way.

An SNP spokesperson, however, said there had been no discussions and no deal would be done on the boundary review. "Given the fall-out and petty score-settling between the Tories and Lib Dems, people will wonder if this whole process has been a waste of time and waste of money. For the coalition to abandon its proposals, after spending £12m on this review, shows just how unreformable Westminster is," the spokesperson said.

Needless to say, the hapless Clegg will be the last to be kept in the loop – while the biggest challenge lie with Ed Miliband, as the election hurdles are deliberately heaped ever higher for Labour.

• This article was amended on 28 November 2012 to add a response from the SNP.