Martyn Eden says both leaders know their position could be under threat if the latest polls are correct and Scotland votes for independence.
On Thursday 18 September Scots will be asked the yes/no question 'should Scotland be and independent country?'.
Our Political Editor told the News Hour there's a lot riding on the vote for both party leaders.
Martyn Eden wasn't shocked they'd decided to go to Scotland instead of staying for PMQs.
"Miliband and Cameron could both lose their roles if Scotland votes yes so I guess they have a vested interest in going.
"It is unusual but not unique in any sense," he said.
David Cameron's denied there's panic in the 'No' camp after a timetable for a transfer of more powers to the Scottish parliament was announced in the event of a no vote.
He said: "I'll do everything I can and let's be frank, there's a lot that the political leaders disagree about but there's one thing we all agree about passionately and that is that the United Kingdom is better off if we stay together."
The latest polls have given the Yes vote the lead after months of trailing behind no.
The SNP said today's announcement by the three main Westminster parties shows how worried they are.
Scotland's First Minister says Better Together has 'fallen apart at the seams'.
Alex Salmond said the offer of a timetable for new powers and the leaders coming to Scotland was too little, too late.
He said: "David Cameron and George Osborne - their one red line issue in setting up this referendum was not to allow devo max, as it's called, so to actually produce something which is far short of that after hundreds of thousands of people have already voted is a sign of total disintegration of the no campaign."
Meanwhile the First Minister has also dismissed press reports that the Queen was worried about a yes vote.
Speaking outside St Giles Cathedral in Edinburgh today Alex Salmond said: 'I want the Queen as head of state, as Queen of Scots of an independent Scotland as her ancestors were.
''I think Her Majesty the Queen, who has seen so many events in the course of her long reign, will be proud to be Queen of Scots, and indeed we would be proud to have her as monarch of this land.
''I had an audience at Balmoral some two weeks ago, but the proper position is you don't discuss these matters in public.
''And I think the statement from the Palace about the Queen's neutrality in this matter is a perfectly satisfactory and perfectly sensible one.
''And, of course, one thing that the polls showed at the weekend, in addition to the substantial move to the Yes campaign, is the enthusiasm of the people of Scotland to have Her Majesty the Queen as our Queen of Scots.''
Premier's Political Editor, Martyn Eden's, spoke with Antony Bushfield on the News Hour: