THIS has been a week like no other.

From a relaxed walkabout with Charles Kennedy in Glasgow's west end to Ed Miliband earnestly rallying supporters in an airless community hall in Cumbernauld, from Gordon Brown's furious denunciation of the Yes campaign in a cramped Labour Party meeting room to a panicky pledge from Johann Lamont, Ruth Davidson and Willie Rennie to agree further powers for Holyrood, the referendum battle is passing in a blur.

Colleagues have witnessed the "battle of Buchanan Street", the moment when a city centre Labour rally ran into a rowdy gang of Yes hecklers, they have seen a Conservative Prime Minister talk of "the effing Tories", and they have watched First Minister Alex Salmond berate Nick Robinson over the BBC's coverage.

The polls have come thick and fast and suggest the outcome is too close to call. The financial markets have become jittery. Banks and supermarket chains, with a little gentle persuasion, have entered the fray. The Governor of the Bank of England has offered his tuppenceworth on the pound. After two years of considered strategising and careful case-building, all hell has broken loose. A game of chess has become the last, bloodied round of a world-title fight.

The sheer intensity of the final full week of the campaign has made it harder to gauge what's really going on. Who is winning? Who will win? Both sides see it very differently, as you would expect. But there is a shared feeling that, after this past momentous week, momentum is all as we lurch towards polling day.

The Yes campaign believes it has the Big Mo. Thursday's YouGov poll appeared to show a small bounce back towards No, in the wake of the week's onslaught, after the same company gave Yes a narrow lead last weekend. But yesterday's ICM poll told of a continued to swing to Yes, putting support for independence at 49 per cent, excluding the don't knows, compared with 44 per cent last month.

Yes campaigners hope the high turn-out, expected to be at least 80 per cent, will favour them as people who are so disillusioned with politics they rarely vote, opt for independence. They are also confident the bombardment of economic warnings this week will not blow them off course. This is different from the experience of Quebec, they say, when economic factors took voters by surprise late in the campaign.

"People have been hearing the scare stories here for years," said one Yes source. "It is less likely they will be influenced. The people who have come to Yes in the past few weeks are pretty solid."

Sustaining the momentum is now what matters for Yes. A sense the campaign is heading to victory brings people on board, as the SNP learned in 2011, and it's an even bigger factor in a straight Yes/No fight than in an election where four or five parties are chasing votes. The Yes message will be simple: "Don't be bullied. It's our time. We can do this." Yesterday, Mr Salmond embarked on a helicopter tour, evoking memories of that 2011 victory, to deliver it.

The No campaign had hoped to be well out of range of marauding Yes bandwagons by this stage. However, Better Together insiders are holding their nerve. The week's events, no matter how nervy, have left them in the lead, no matter how narrowly. They believe the momentum is now back with them and the First Minister's "victory tour," as they are calling it, is an attempt to maintain the illusion of surge that is no longer really there.

"We expected the Yes campaign to try to play out a score draw on the facts, create confusion, and hope they were close enough to make an emotional pitch in the final two weeks and to give the impression they are winning," said one source. "It's an old tactic but they've now been hit with an avalanche of uncomfortable facts and people are taking notice."

Better Together insist its canvass returns tell a different story from the polls, with stronger support for a No vote. The campaign also believes the dwindling but still significant band of don't-knows is more likely to break for No.

Yes also says its polling is good, so it's impossible to know for sure who is right (or if both are wrong). It's certainly still all to play for. If the past week has felt like a long time in politics, the next five days could be an eternity.

Editor's note: the original online version of this article was incorrect. We apologise for the confusion.