Keen students of the constitutional argument between Unionists and Nationalists which has bedevilled Scottish politics for more than 30 years might have had pause for thought in the centre of Edinburgh yesterday.

If they had been passing St Andrew’s House, formerly the seat of Unionist government in Scotland but now captured by a devolved Nationalist administration, they would surely have had to do a double-take.

For there, outside the front door of this example of dour 1930s architecture, were two politicians from either side of that divide exchanging cheerful banter with each other and generally enjoying each other’s company as they fended off questions from nosey and sceptical reporters.

Those reporters had arrived hoping, as reporters do, for a bit of a bust-up. Jim Murphy, Secretary of State for Scotland in Her Majesty’s Government, was meeting the Scottish Cabinet, a group of politicians with one aim in mind — the break-up of the Union so robustly championed by the indefatigable Mr Murphy.

After the meeting, the deadpan Mr Murphy emerged alongside the more jovial John Swinney, the Nationalist Finance Secretary, and the two proceeded to try and convince us that all these reports of verbal punch-ups at 400 miles distance between the two governments were figments of the imagination of scrurrilous political hacks with little better to do.

Yes, they had discussed the economy and how to pull individual Scots and Scottish businesses through the recession. Yes, they had discussed the constitution, in the shape of the recommendations from the recent Calman Commission. And while there were disagreements, they really liked each other and couldn’t wait for more meetings like this one.

As if to prove their point, the two then went into a routine which, we hope, was not rehearsed. Mr Murphy, showing a certain lack of respect for Alex Salmond, the First Minister, ventured that Mr Swinney would make a fine leader of his party — a position occupied of course for now and the foreseeable future by Mr Salmond. Mr Swinney, laughing fit to burst and in a reference to his rather undistinguished time as SNP leader a few years ago, replied: “Oh, we tried that . . . it didn’t work.”

The meeting, said Mr Murphy, whose charm offensive on the Nationalists appears to be limitless, had been simply excellent and neither side had let little things like the SNP’s complaints about alleged cuts in the Scottish budget spoil the party atmosphere.

But the hacks persisted and caught a first glimmer of some real division. Mr Murphy had invited Mr Salmond to join the steering group set up to implement the Calman Commission recommendations. Mr Salmond, who has been attempting to portray the Calman Commission as a Unionist set-up, predictably said “No”. Mr Murphy suggested that was a shame.

For their part, the Nationalists tried to tempt Mr Murphy into agreeing that those elements of the Calman report which recommend transferring powers over things like airguns and speedlimits to Holyrood should be implemented without delay. It was Mr Murphy’s turn to say “No”. Calman, apparently, according to the Scottish Secretary, like truth, is indivisible.

And so it went on. Behind a cascade of verbal blancmange from the two, little hints of conflict insisted on showing themselves.

But these were really quibbles. We hacks were missing the big picture.

What we should have been concentrating on was the undying affection which exists between Mr Murphy and his Nationalist counterparts in Edinburgh. It’s just that it would be rude to advertise it, wouldn’t it?

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