He came, he spoke, and in a week we will know if David Cameron’s “head and hearts” plea to the people of Scotland has managed to save the union.

The fear-factor script that has characterised month after month of the No campaign has been dumped by the Prime Minister and replaced with impassioned, personal appeals not to tear up 300 years of history, not to split “this family of nations”, nor to treat the referendum as just another opportunity to kick “the ‘effin Tories”.

It was a carefully choreographed performance. Delivered in the relative safety of the glass and steel atrium of Scottish Widow’s Edinburgh headquarters in the heart of the capital’s under-threat financial services district, Mr Cameron perched himself on the edge of a wooden stool, and like a supplicant Caesar, stretched out a largely unwanted – for many Scots - Conservative hand of friendship to claim he would be “heartbroken” if the United Kingdom was “irreversibly” torn apart.

Playing the role of a political heretic, though admittedly a leader in charge of only one MP north of the border, he nevertheless said he “cared far more about my country than I do about my party. I care hugely for this extraordinary country, this United Kingdom that we’ve built together.”

Away from the capital, Ed Miliband was in a community centre in Cumbernauld delivering almost the same speech, with the same words, with the same “head, heart and soul” message. It was a remarkable, almost unprecedented show of unity of purpose. Miliband versus Cameron: the two are billed to go head-to-head in next year’s general election. But both know their chances of surviving that far are slim, if on their watch Scotland begins its voyage from the union next week.

“Stay with us,” urged Mr Miliband, “so we can change Britain together.” He said English, Welsh and Northern Irish hearts “lie with you”.

Mr Cameron, trying to emphasise what he called “the scale” of next week’s vote, said it wasn’t about “the next five years - it’s a decision about the next century”.

With Nick Clegg in the Borders, there was a trinity of faith, hope and buried enmity centred on a hastily arranged Westminster belief that their unscheduled campaign tour would somehow dent the momentum of the breakaway Yes campaign.

But it looked too staged, too safe – and perhaps too late. Downing Street limited the risk and the exposure that Mr Cameron faced. Scotland, 25 years after Margaret Thatcher, remains toxic territory for Tories. So there was no bear pit, no soap box, no chance the separatists could disrupt the away-day.

The location of the PM’s visit was as tight a secret as a Budget speech. “We heard rumours,” said one of Scottish Widow’s sales team, but "nothing official”.

The employees who eventually gathered around Mr Cameron in the atrium coffee area, were trusted to be gentle with the PM. And they were.

Having been outmanoeuvred by Alex Salmond over the timing, content and terms of the referendum debate, the Prime Minister almost used Edinburgh to emotionally rejig next Thursday’s ballot paper. "No" no longer means "No". Instead, Mr Cameron, promised “a vote to stay in the United Kingdom will trigger a rapid and comprehensive move to make sure that Scotland has even more powers to determine its own future.”

Gordon Brown mapped out the timing and Mr Cameron acknowledged as much. “Gordon was spot on,” he said. The all-party union love-in was now in a strange unfamiliar country called consensus. A Scottish taxation regime, control over welfare; Scotland could have “the best of both worlds”. The referendum, he said need not be about Scotland versus Britain. And no – no shared currency.

Both Mr Cameron and his regular adversary across the Dispatch Box at PMQs were now signing from the same kirk hymn sheet. Family, Scotland’s history and geography, the future as important as the past, togetherness, friendship, common ties.

This was the should-have-been campaign, the positive rather than the negative. Were minds changed in atrium? Most admitted the PM confirmed their voting plans for next week. But one employee said: “the real question none of us can answer yet – is this the failed campaign?”

But outside in the streets of the financial district, there were rumours. “Is Cameron hiding in there?” asked two women carrying blue and white Yes banners. Another man, also carrying a Yes card, gave an indication of the ferocity-in-waiting had Mr Cameron decided on to take to Edinburgh’s streets and meet the people. “I know he’s in there, I can smell him,” was one shout.

Another shouted “Let him enjoy it. It’s his last day in Scotland.”

Other employees from nearby bank headquarters gathered to watch the PM’s black Range Rover zip out of Scottish Widows' underground carpark. One asked “What was the point of that?”

Nick Clegg decided the Borders were safe enough to engage the locals. He was wrong. Under the statue of Sir Walter Scot, the writer credited with reinventing Scotland as palatable Victorian entertainment, the deputy Prime Minister’s attempts at engagement were met with shouts of “Liar!” from placard-waving Yes supporters. Gladstone and Lloyd George are usually Liberal trump cards in these parts. No longer.

Serial cries of “Nobody wants you here,” might have contributed to Mr Clegg not hanging around long enough for Marion Livingstone, a No voter, to catch a glimpse of the DPM.