The idea that Scotland’s a decisively more left-wing country than the rest of the UK is at least in part a myth, perpetuated largely by the marked disparity in the Tory vote share north and south of the border, combined with the associated myth that the SNP are a left-wing party now.

In 2007 and again in 2011, it’s clear that many natural Tories voted SNP. Some did so, especially in 2011, because the SNP’s position on taxation was just as right-wing as the Tories. Many many more did so, especially in 2007, simply because the SNP could end Labour’s hegemony at Holyrood. Others no doubt saw a kindred spirit in Alex Salmond, despite his leftwing views on currently reserved matters like defence and international affairs.

The deal was always this – we’ll vote for the most credible party to the right of Labour (to be clear, I don’t regard Labour as left-wing any more either), but in the unlikely event you ever manage to bring your referendum forward, we’ll vote no. I’m sure some business types have genuinely come round to independence, especially given the SNP desire to race to the bottom on corporation tax, but for most I suspect that remains the deal. Run Scotland, Mr Salmond, unless and until the Scottish Tories get their act together.

But what about the SNP majority now? No-one expected that, not the over-exposed Mr Curtice, not the swathes of new SNP backbenchers, not the Great Puddin’ O’ the Chieftain Race himself. And certainly not the Tories who went tartan, who now face a referendum which they must fear losing, given the relative quality of the leadership and the relative campaigning nous on both sides.

Might tactically-minded Tories out there not now wish to pull the balance back in the other direction, take any opportunity to bring the SNP back to minority levels? The Nats proved they could run a competent minority administration – in fact, their period of minority was probably the most competent in Holyrood’s history.

If Bill Walker resigns as an MSP (and Kate’s right, he should), what happens in Dunfermline? Bill won with a narrow 590 majority, and the by-election dynamics would be entirely different. If it’s a seen as a local vote for against independence, Labour would have to be pretty confident even if John Park doesn’t contest it, as Kate suggests. That 590 majority looks even smaller when you consider the almost 8,000 combined Tory and Lib Dem votes from last year. Sure, the Nats’ election machine remains the most formidable ever assembled in Scotland, but this is not natural Nat territory.

I love by-election drama, and I think Bill has a moral responsibility to let his constituents be represented by someone who’s not a wife-beater, but if I wouldn’t be surprised if the SNP leadership were saying “Go!” in public and desperately hoping in private to keep their effective majority exactly where it is today.

Edit: I’ve taken the other Bill Walker out, the former Tory MP. The coincidence in naming amused me, buy think I meant Nicky Fairbairn anyway and I don’t want to associate the Tory one with domestic violence.