DAVID Cameron is to lead a charge of Westminster Cabinet ministers to Scotland in a fight to save the United Kingdom in what is already being dubbed the Battle for Britain.

The Prime Minister will head north in the coming weeks to reinforce the Coalition Government's message of the importance of the Union.

A Downing Street spokesman said: "There's going to be a lot of discussion. He will certainly be making the case for the Union.

"He is engaged in this issue and I would expect all Government ministers to do the same. I would expect a lot of activity."

Scottish Secretary Michael Moore will also be "holding events in Scotland" to listen to the public's views and explain Westminster's position as part of the Coalition Government's two-month consultation on its proposed independence referendum.

A summit would shortly be held between Mr Cameron and First Minister Alex Salmond in Scotland, a senior No 10 source added.

Tomorrow, Mr Salmond will come face-to-face with Deputy Prime Minister Nick Clegg, for the first time since he announced the poll would be held in the autumn of 2014, at a meeting of the British-Irish Council in Dublin.

At Prime Minister's Questions yesterday, Mr Cameron and Ed Miliband, the Labour leader, united in a pledge to fight to keep Scotland in the Union. Meanwhile, Mr Salmond warned Westminster politicians to "butt out" of the constitutional debate.

Johann Lamont, the Scottish Labour leader, told The Herald she would be willing to share an anti- independence platform with Mr Cameron, unlike Jim Murphy, the Shadow Defence Secretary.

She said it would be difficult because Conservative policies were damaging the economy but added: "On the basis of whether we should be in the United Kingdom or not, we're on the same page."

Ms Lamont has tabled a Holyrood motion for this morning, which recognises the Scottish Government has a mandate to call a referendum on the constitutional future of Scotland – something the Coalition has suggested may be illegal – and calls for cross-party talks on the issue. Westminster had warned SNP ministers could end up in the UK Supreme Court if the Scottish Parliament held its own independence poll.

However, it looks like there will be no single anti-independence campaign leader in Scotland. Instead it is likely to involve an alliance of politicians from across the spectrum, along with business, civic leaders and academics.

Lord Reid, the former Labour Home Secretary, and Alistair Darling, the former Chancellor, have both ruled themselves out of leading it.

After Mr Salmond dramatically announced he wanted to hold a referendum in autumn 2014, both the UK and Scottish Governments made clear they were now willing to negotiate a way through the constitutional arguments on holding an independence poll.

Asked if he would enter into negotiations in a constructive manner, the First Minister said: "I'm always constructive about these things."

He added: "As long as it's recognised, the mandate for the Scottish Parliament to organise and hold the referendum, it must be a referendum built in Scotland and decided by the Scottish people - I'm sure politicians north and south of the Border are capable of coming to agreement at some time this year on the ground rules for such a poll. Certainly, that would be my attitude."

Earlier, Mr Moore, asked if Mr Salmond would set the terms of the referendum, replied: "The First Minister recognises we need to talk about this and to work together because what people will not forgive is if our bickering gets in the way of Scots making this decision that affects our future."

As the inter-governmental talks get under way, one senior Coalition figure indicated the UK Government's key red line would be against having a "devo-max" option on the ballot paper but he indicated there might be some leeway on allowing the Scottish Government's timetable for a vote.

Former LibDem leader Sir Menzies Campbell said: "Once the dust has settled, it is obvious to me the two governments have to sit down to serious negotiations. Friction between Westminster and Holyrood will only obscure the issue of independence or not and what is clearly necessary is a decisive outcome and it's in the interests of both parliaments this should be so."

The Fife MP added: "There's bound to be a bit of grandstanding in public but we can put up with that if there are serious discussions going on in private."

Earlier, Mr Cameron told MPs he "passionately" believed in preserving the Union, and taunted the SNP for seeking to delay a ballot. He said: "I sometimes think when I listen to them it is not a referendum they want, it's a never-endum."

Mr Miliband called for immediate cross-party talks to deal with the process of how a single-question referendum could be held under the oversight of the Electoral Commission. "We must make the case for the Union; not simply against separatism but the positive case about the shared benefits to us all of Scotland's part in the United Kingdom, the shared economic interests, the shared institutions like the NHS, our defence forces and the BBC and above all the shared values we hold together."

Meanwhile, the SNP's Angus Robertson accused the Prime Minister of "trying to emulate Margaret Thatcher by dictating to Scotland" when his party had fewer MPs north of the Border "than there are giant pandas in Edinburgh Zoo".