But it wasn't an unthinking response on Salmond's part. He had considered the subject a great deal, seeing in the European project a way to persuade Scots that breaking up the UK was not an inward-looking narrow-minded piece of constitutional vandalism but instead a supposedly expansive, internationalist act. Salmond had learnt at the feet of Jim Sillars, the winner for the SNP of the famous Govan by-election in Glasgow in 1988. Sillars, an extraordinary autodidact and thinker of the kind the Labour movement used to produce, has always pursued arguments where his intellect takes him. 

He started as a left-winger, devising the independence in Europe concept in the 1970s partly because he viewed Europe as a means by which to corrode and destroy the authority of the British state. When he left Labour, via a failed breakaway Independent Scottish Labour Party, Sillars joined the SNP and introduced the party leadership to the idea. The policy was adopted and when Salmond became leader in 1990 he turned it into the centrepiece of his platform.

Sillars and Salmond, as is often the way in small parties, then fell out spectacularly. Sillars went sour on the EU, pursued a career in business and, with the Tory former Secretary of State, Sir Malcolm Rifkind, eventually helped  lead the Scottish end of the campaign to keep Britain out of the euro in 2000. But by that point Salmond had been gifted an open goal: Scottish devolution. The Labour establishment had adopted the cause of home rule as a defensive measure, to prevent Conservative governments based in London "imposing" policy north of the border. New Labour, after holding a referendum in 1997, created the Scottish parliament. Advocates of the policy such as George Robertson declared at the time that devolution would kill the SNP "stone-dead".

It didn't work, and in the election last year Salmond's party ended up anything but stone-dead. He won an overall majority, leaving the Unionist cause leaderless ahead of the promised referendum. It would all be perfectly set-up for Salmond, if only it wasn't for what is happening right now on the continent. Salmond, for most of his extraordinary career, has been swimming with the tide of history on Europe. Now it is running against him.