Way back in October last year we analysed what now seems to have become the key plank of Unionist argument against independence in the wake of Brexit – the idea that because Scotland does more trade with the rest of the UK than it does with the EU, independence would be economic suicide because Scotland would be sacrificing “the UK single market” (a thing that doesn’t actually exist ) for a much smaller one.

It’s a completely idiotic position, but to be honest we didn’t do a very good job of boiling the counter-argument down to something snappy and quoteable, so let’s have another go and see if we can manage something a little better.

1. After invoking Article 50, the UK has two years to negotiate a trade deal with the rest of the EU. If it doesn’t have one in place by then, it’ll have to trade with the EU (and in fact with everyone else too) on World Trade Organisation terms, which pretty much everyone agrees would be a catastrophic outcome.

2. Therefore, one way or another there WILL be a trade deal in place between the EU and the UK by 2019. It’s likely to favour the EU, for obvious reasons, but it’ll still be better for the UK than WTO terms.

3. An independent Scotland would be in the EU. Therefore it would continue to trade with the rUK just as it does now – except that Scotland, as an EU member, would now be getting preferential terms.

The idea that the rUK – which sells considerably more to Scotland than it buys – was suddenly going to stop trading with Scotland was always mind-numbingly fatuous. It’d be like shooting yourself in the face because you had an itchy nose.

But when you remember that the UK has to agree a trade deal with the EU by 2019 or be absolutely screwed, it turns from stupidity to pure farce.