DAVID Cameron wasted no time in calling for "English Votes for English Laws" (Evel) after the referendum.

Within an hour or so of the result being declared he promised to deliver further devolution to Holyrood - but insisted that as MSPs took greater responsibility for policies in Scotland, English MPs must in future decide on issues affecting only England.

Labour cried foul. Under Evel, they could find themselves forming a UK Government without a majority in England. A severely hamstrung government, in other words. If Mr Cameron's move was a trap, Labour should have seen it coming. The Conservatives have campaigned for Evel at the last two elections and Mr Cameron was oblivious to Labour's indignation when he discussed the issue before a committee of MPs on Thursday.

The principle of Evel is simple enough but, as so often, the devil is in the detail. So far no firm proposals have emerged, but Mr Cameron indicated support for an idea put forward by Andrew Tyrie, the Conservative MP for Chichester.

In a recent think tank paper he proposed a watered-down version of English Votes for English Laws. Is it the lesser of two Evels?

The starting point for consideration of Evel is the McKay Commission, which reported in 2013. It came up with various ways to give English MPs a greater voice in framing legislation on English-only issues but was wary of creating two classes of MP and, ultimately, rejected English Votes for English Laws on the basis that a UK Government should be accountable for decisions made during its term in office.

Critics said it bore all the hallmarks of a thorough, thoughtful, well-researched fudge.

Mr Tyrie was among them. He argues the recommendations offer "inadequate protection for English interests", arguing that without an ultimate veto, England could still have "measures foisted on it that a majority of its MPs do not support".

In his study, he rules out an English Parliament, which he says would inevitably lead to the creation of a separate English government. Federalism, in other words, an arrangement he describes as "superficially appealing" but which he regards as doomed because of the size of England.

Here he is in agreement with another passionate opponent of Evel, Gordon Brown, who spoke during the referendum campaign (a good deal more cautiously than he has since been credited with) of a creating a new constitutional settlement "as close to a federal state as you can be in a country where one nation is 85 per cent of the population".

Mr Tyrie warns the UK Government would be "weak and marginal" compared with the English government in charge of the things that matters most to people's everyday lives: health, education, transport, justice and the rest. A staunch supporter of Evel, Mr Tyrie describes the idea as nothing less than "the minimum necessary to stabilise the Union in the long term".

Perhaps surprisingly, given all that, he rejects what he calls the "full-strength version," under which English MPs would be able to push through laws against the wishes of the government of the day. That would create an English parliament by default, he warns. Instead he says English MPs should be responsible for bills judged to be English-only up to the final stage of their passage through the Commons. At the Third Reading, however, the whole house would vote, effectively giving a government without a majority in England a veto over English-only legislation it opposes.

The government would not be able to make changes to the legislation so there would be a "double veto" on both sides.

It would give both the government and the English majority strong incentives to compromise, he argues. Governments would have to learn to bargain, he argues, just like administrations in the US.

Lots of objections to Evel remain, not least the thorny question of defining "English-only". Rutherglen and Hamilton West Labour MP Tom Greatrex says only eight out of 464 pieces of primary legislation between 2001 and last year applied only to England. However, with the Prime Minister appearing to back Mr Tyrie's Evel-lite, the battle between Labour and the Conservatives over the issue may have become a little clearer this week.