Imagine if the Scottish Tories had backed a pro-UK gathering at which a “satirical” troupe of “comics” had put on a revue involving a mock rap in which they called a prominent Nationalist a “dyke.” The sky would have fallen in. The First Minister would have immediately issued a thundering statement on discrimination. Twitter would have gone wild in its Scottish extremity with demands for the Tories to apologise. SNP MPs (John Nicholson springs to mind) would have gone into full pious head-shaking mode about the Tories being a bunch of nasty dinosaurs.

Yet the position was reversed at the weekend, and what do you know? When a Nationalist comedian at the Scottish Independence Convention referred to the leader of the Scottish Tory party as Ruth “Dykey” D in a mock rap this was hailed as hilarious by the SNP MP Joanna Cherry and assorted other Nationalists. Have you no sense of humour? It’s just a wee bit of banter! Comedy is subjective! Another usually sensible SNP MP even accused opponents of playing politics with homophobia.

This will not do. It is quite simple. The routine was not only deeply unfunny, a crime against comedy in a country that produced the genius Billy Connolly, it also used a term against Ruth Davidson that should not have been used. Call my view political correctness if you must, I prefer to think of it as basic good manners and respect for others, a habit which most of us by adulthood have learned.

What fascinates me most though about this incident are the contortions that SNP MPs and MSPs will go through in order to never, ever criticise anything related to the Nationalist movement or, indeed, SNP policy. ‎There are plenty of bright, decent SNP MPs and even a few MSPS, yet they are banned – prohibited – from criticising party policy or the leadership. This is because the leadership knows that the Nationalist movement is wide but not deep, containing socialists and free-market tartan Tories. The only way to hold it together is iron discipline and a refusal to accept any dissent. Keep it all concentrated on one, constitutional aim.

This helps produce a sinister mindset in the wider Nationalist movement, in which all criticism must be deflected to defend the cause come what may. Logic is turned upside down, values are inverted to fit the party line.

All healthy parties feature plenty of public dissent – it is a pressure valve. Tory MPs publicly criticise the Chancellor when his budget contains a cock-up or the government is making mistakes. ‎The Labour party has taken dissent and chaos too far in the last year, but even so it has always had a lively debate at its heart, even during New Labour. Blair declined to expel Corbyn.

The SNP‎ allows none of this. Which somehow leaves it defending bad jokes or being slow to condemn the use of a homophobic term about the leader of another party. Nice.

Let’s hope some of the SNP’s leading figures have a rethink and a good hard look at themselves and their movement.