The orthodoxy at Westminster is that Scotland and Northern Ireland have been discounted for UK general elections. Not just this one, but for a couple of generations or forever.
The Tories think they might be able to sneak their present seat and perhaps another, like Perth maybe (they’re culturally conditioned to always think this about Perth….). That won’t make any difference to the make-up of a UK Tory government, of course – it’ll still be made up entirely of England (and maybe Wales) MPs – but it might help with the (broadly true) narrative of modest Tory recovery in Scotland.
Labour accepts that it’ll be lucky to hang on to its present seat and is hoping for a freakish result in maybe one other seat in Scotland. Its wild hope, too, is that maybe it’ll do well enough to do a ‘confidence and supply’ deal with the SNP where the SNP provides votes at critical times to beat the Tories in return for ‘things’ for Scotland. This of course also involves a UK government made up entirely of England (and maybe Wales) MPs.
The Lib Dems have ruled out a deal with Labour and have no hope of increasing their numbers in Scotland so, in the event they hold the balance of power, see ‘The Tories’ above.
Notice that all of these options have the same end result. Scotland is ruled by a wholly England (and Wales…) government? But notice, too, that all of the parties at Westminster accept that the notion that SNP MPs might have a say in the government of England is a vote-killer (which is why Labour won’t consider even a theoretical coalition) and so out of the question.
Unionists therefore accept that all of their possible outcomes involves forcing upon voters in Scotland something they know is anathema to voters in England. And that’s why this election is, in Scotland, all about independence.
Footnote: I always discount the Scottish Office since it’s just a legal necessity, isn’t an executive department and has no money.