Nick Clegg has likened Alex Salmond to a Japanese WW2 soldier fighting in the jungle after the war ended and urged him to "call it a day" on a second referendum and accept the will of the Scottish people.

Speaking at his regular Whitehall press conference, the Deputy Prime Minister told journalists: "Alex Salmond reminds me of a Japanese soldier found in the jungle 20 years after the war had finished, still ducking at every shadow, thinking the war was still on. At some point, you have to call it a day and (accept) that the people have spoken.

"After a ferociously contested referendum that has dominated debate north of the border for years, not just months, there was a pretty emphatic result. Surely, even if we might not agree on a lot, Alex Salmond, myself and others can agree we are democrats and at the end of the day you have to abide (by the result)."

He stressed: "I have gone through referenda, which have not quite gone the way that I want (on PR). You don't then immediately the next day say you don't like the result, let's have another crack at it. That's not the way we use referenda in this country and we shouldn't."

Last week, the First Minister, who before September 18 repeatedly said he believed a referendum on independence was a once in a generation event, talked of betrayal on the vow of more powers issued by the the leaders of the Conservatives, Labour and the Liberal Democrats.

But he made clear "circumstances obviously can change" and suggested that any reneging on the promises made would be "a very, very substantial change of circumstances".

Mr Clegg also said he had some "considerable sympathy" with the view expounded last week by Gordon Brown that David Cameron and the Conservatives were now seeking to use the English votes for English laws issue for purely party political advantage.

The former Labour Prime Minister also warned that full devolution of income tax powers to Holyrood would lead to Scottish MPs becoming "second class citizens" at Westminster because they would be banned from taking part in key finance votes such as the Budget. This, argued the MP for Kirkcaldy, would inexorably lead to the break-up of the UK.

The LibDem leader noted how the Tories had sought to block constitutional reform such as that for the House of Lords, PR and party funding at "every turn".

"The one thing which might be of narrow political advantage to them, which, under their scheme, is basically giving the Conservatives the whip hand at Westminster even though they only got 39 per cent of the vote in England; so I have a lot of sympathy with Gordon Brown, saying that's not serious constitutional reform."

However, Mr Clegg insisted there was a balance to be struck on dealing with the so-called English Question and is proposing to have an English Grand Committee stage of a Bill, which is primarily England only, and which Scottish MPs would be banned from. But, thereafter in following stages of the Bill, Scottish MPs would be able to vote on Westminster's "final say".

A senior LibDem source later accepted that this could, in theory, mean Scottish MPs could block or pass a piece of legislation contrary to the wishes of English MPs but noted it would be "extremely difficult" for such a party to push this forward and would have to justify such a move to the public.

The DPM stressed that to make the English Grand Committee fair and which would "strike the right balance", then it would have to be made up of members roughly in proportion to how the parties did at the General Election.

"That's terrifically important," declared Mr Clegg, saying that that has been how constitutional change has been tackled in the past such as at Holyrood, Cardiff, Stormont and London.