AS any star knows, when planning a comeback it is best to start small and build to big.

Play a back room and a green room or two before moving on to the starlight lounges and Vegas, baby. Gordon Brown, the man least likely to don a velveteen tux and swing a microphone, will demonstrate this unwritten rule of showbusiness when he rocks up to a small-ish venue in Glasgow's east end next week.

What do you mean, Gordon Who? How quickly those caught up in the long, giddy whirl of a neverendum referendum campaign forget. Gordon, you know, the MP for Kirkcaldy and Cowdenbeath, former Chancellor of the Exchequer, ex-Prime Minister of the UK? The one impersonated by Rory Bremner? That's the fellow.

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As revealed by The Herald, Mr Brown will be hitting the road with the chief aim of throwing a jack into the works of the Yes campaign. He has failed to make many speeches in the House of Commons, and at one point during his long, self-imposed recess he claimed he was an "ex-politician", but make no mistake: the man who would be king of the No campaign - and there are a lot of wannabe contenders out there - is coming back.

Is this the best thing to happen to the Yes camp since Colin and Christine Weir won the EuroMillions jackpot? Put it another way, will Mr Brown prove to be as toxic an addition to the No campaign as his old boss, Tony Blair, would be? (Speaking of the TB half of the once popular duo, those who cannot bear too much political excitement in the one week should know that he is far too busy with other matters to become involved with the independence campaign. Near the top of the Blair to-do list is deciding how much to donate to Labour. How pleased to the point of sobbing Mr Miliband must be at that news.)

That Mr Brown's intervention should cause a stir is in part a result of his status as a former premier, and in part a comment on the No camp's inability to put a face on their campaign that voters can warm to. Alistair Darling has so far proven himself to be as grey as his hair, Scottish Labour leader Johann Lamont could never be mistaken for a ray of sunshine, and the leaders of the other parties in the pro-Union coalition could hardly fill a bucket never mind a hall in Glasgow. The No camp is in need of a name and a face, and Mr Brown has as strong a claim as any to be "it".

Whether this is a good or bad thing depends on how one views Mr Brown, his personality and his political past, and the nature of the independence campaign. It is notable that he is taking part in the battle under the flag of United with Labour rather than Better Together. That he is not throwing in his lot with the pro-Union coalition of Scottish Labour, the Liberal Democrats and the Tories, is telling. Viewed negatively, it could be a sign that despite protestations to the contrary, the past spat with Alistair Darling, which almost led to Mr Darling's sacking, has not been forgotten, and that Mr Brown's ability to be a team player is once again in question. There have been few memoirs by former Labour ministers which have not contained a "my fights with Gordon" chapter. As a teacher might say, Gordon does not play well with others.

But his go-it-alone tour can be looked at in another light. For those who do not like their politics to be all Kumbaya and coalitions, Mr Brown's solo act is a welcome outbreak of red-blooded tribalism. Never underestimate the power of tribalism. It was this that helped Scottish politics, helped Scotland, through many a bleak night. Moreover, the general antipathy of Scots towards snuggling up with bedfellows who might otherwise turn one's stomach should not be taken lightly. But there is a far more important reason, as we shall see, for Mr Brown to be sailing under the Labour flag.

Before considering that, there is the hardly inconsequential matter of Mr Brown's performance in office to ponder. Now, to the Yes camp, bringing up the fact that it was Mr Brown at the helm when the recession hit the fan in 2008 might seem like a shoo-in. True, Mr Brown is vulnerable on that score, but so is Mr Darling and thus far that charge has largely failed to stick. Like Mr Darling, the man who kept the cashpoints functioning, Mr Brown could argue that he has been through the fires of economic hell and knows what he is talking about when he warns of trouble ahead should Scotland opt for independence. In any case, when it comes to the word recession, Mr Brown, like Mr Darling, never allows it to go out on its own without being accompanied by the term "global". In addition, the former premier is a veteran of the prawn cocktail offensive: he can speak the City's language, knows the buttons to press. It is hard to imagine that what he says on independence will not be heeded in the boardrooms of Edinburgh and London.

But that is not why his intervention could prove to be crucial. Business is capable of coming to decisions on its own, and the trickle expressing scepticism is turning into a steady flow. Whether that helps the No campaign, or convinces undecideds that if the money men are agin independence then that is a good reason to back it, we shall see.

Where Mr Brown could prove dangerous to the Yes camp is not in his attractiveness to business but in his appeal to Scotland's big, red heart. Define that heart as socialist, left-leaning, socially aware, community minded, describe it any way you like, but its beat is unmistakeable. The great strength of the Yes campaign thus far lies in presenting a positive vision of a successful, fairer Scotland without the incurrence of too much risk and upheaval. Mr Brown's mission, now that he has chosen to accept it, will be to argue that a fairer Scotland is only possible if the Union stays together. In short, he will be asking Scots to consider, in their heart of hearts, whether the lone parent in Glasgow does not have more in common with the single mother in Gateshead than she does with an independence-supporting businessman wherever he lives. The Nationalists have stolen Labour's clothes on fairness. Mr Brown now wants those ragged trousers back.

What impact this has on the vote depends on how one views this referendum. If it is genuinely about creating a fairer Scotland then the No camp have found a fighter who is the equal of the First Minister and his deputy in explaining how that is best achieved. Equally, those Labour supporters swithering over how to vote, the same folk utterly uninspired by the party at the 2011 Holyrood election, will at last have some old-time religion with which to fire themselves up. Mr Brown is no Sinatra, but it could just be he is the man with the right song at the right time.