Evel: PM faces growing pressure from his backbenchers to limit voting rights of Scots MPs

The proposal has been put forward by Iain Stewart, the Scots- born Conservative MP for Milton Keynes South, as a quick and simple answer to the West Lothian question. It came as the dispute over Evel intensified yesterday following ­Thursday's publication of the Smith Commission report on devolving more power to Holyrood.

In Glasgow yesterday, Labour leader Ed Miliband hit back at the Prime Minister's claim that Lord Smith's ­blueprint should prevent MPs north of the Border from voting on income tax in England.

Meanwhile, Labour and the SNP each accused the other of attempting to water down proposals for more powers.

Mr Stewart, who grew up in ­Hamilton, said legislation affecting England should require support from a "double ­majority" of MPs from south of the Border and the whole UK.

He said the system would not require separate committees of English MPs or the creation of an English parliament - an idea backed by some Conservatives - but argued it was a "workable model that would address the English dimension of devolution".

He said in a letter to The Herald: "This would mean that Scottish MPs would still have the right to contribute to debates and votes on matters which apply only to England but which can often be reasonably argued to have a bearing on Scottish affairs. It would also, however, require explicit English consent to be introduced."

Mr Stewart's plan is similar to a scheme devised by Tory MP Andrew Tyrie. He has said a UK Government dependent on non-English MPs should be able to block - but not alter - legislation brought forward by an English majority. Such a "double veto" would force compromise, according to the Chichester MP.

Mr Cameron indicated his support for the idea when he recently discussed the issue before Mr Hague's Cabinet committee. It is due to come up with firm proposals before Christmas.

The Prime Minister pledged to ­introduce Evel in the immediate aftermath of September's independence referendum. He said the measure, ­popular with Tory backbenchers, was required to balance Holyrood's growing autonomy.

Labour, who are likely to rely on Scots MPs to form a government, have fiercely resisted the plan, setting up a major battle over the issue in the run-up to next May's General Election. They have accused Mr Cameron of attempted "gerrymandering" over Evel and claim the Tory leader is trying to create a separate English Parliament at Westminster that his party can control if Labour win on May 7.

Many believe a Labour administration would struggle to get its budget passed if it did not have a majority of English MPs, and could potentially even fall.

Many also warn Evel could prevent an MP from a Scottish constituency ever becoming Chancellor or Prime Minister, because the convention of collective responsibility demands ministers vote for their own policies.

Mr Miliband insisted the Smith Commission proposals, giving Holyrood control over income tax,

guaranteed Scots MPs the right to vote on UK budgets even if Evel were to be introduced.

He said: "We're all going to abide by those recommendations and the recommendations of the Smith Commission could not be clearer about the fact that Scottish MPs will continue to vote on the budget and indeed on income tax. It's there in black and white in the Smith Commission."

He spoke out after Mr Cameron's spokesman said Evel could apply to income tax votes, despite the Smith Commission stating: "MPs representing constituencies across the whole of the UK will continue to decide the UK's budget, including income tax."

Meanwhile, Labour accused the SNP of ­mounting an 11th-hour bid to remove the power to create new benefits from the commission proposals. The accusation was denied by the SNP, who said that Labour, the Conservatives and LibDems blocked their call for welfare to be devolved in its entirety.