There are two particular reasons why Gordon Brown's latest intervention in the debate about Scotland's future is welcome. The first is simply that it is good to have him back. This newspaper has had its agreements and its disagreements with the former Labour leader over the years – and he with us. But there is no virtue in needlessly refighting old battles or endlessly brooding on the past. Mr Brown is indisputably a big, serious figure in the national debate. Our politics are the poorer without his voice on the large subjects facing the nation. And the Scottish debate, in which his status as a thinker and campaigner for more than 40 years is beyond challenge, is arguably the largest of them all.

The second reason is that Mr Brown's recent speeches and his Guardian article this week are part of the more positive tone that is now marking the no campaign. This too is something to be welcomed. In the early part of this year, the anti-independence campaign allowed itself to become too negative and to sound too hectoring. UK ministers would go up to Scotland and would warn the Scots of the dire consequences that would follow from separation. This was well-intentioned but counterproductive. As Mr Brown pointed out this week, it enabled the nationalists to present the referendum as a choice between Britain and Scotland rather than competing visions of Scotland. The consequence was an instant narrowing in the polls.

That narrowing has ceased now, at least for the moment. Last week's "poll of polls" showed a 16-point lead for the pro-union side over the pro-independence side. With just over three months to go until the referendum, the formal campaign period has also now begun. The shape of the argument has evolved too. There is still a long way to go before 18 September. But, as Mr Brown put it this week, pride in Scotland is perhaps now more clearly common ground between the two sides, not the property of the nationalists alone. The no campaign is now accentuating the positive. It is underscoring its Scottishness as well as its Britishness, and emphasising its Scottish patriotism as well as its belief in the UK.

This greater positivity is not all down to Mr Brown. He is one part of the more positive anti-independence approach, not the sole incarnation of it. Mr Brown is wrong about some things too. He prefers to campaign against independence from a strictly Labour platform, not from a non-partisan Better Together one, alongside Conservatives and Liberal Democrats. It is his choice. But the way that all the Better Together parties – including the Scottish Tories – have recently rallied behind further devolution proposals has probably done more than anything else to instil the welcome new positive tone to the pro-union campaign.