[T]he SNP appears to have given no thought to the perceived legitimacy of a nationalist-tinged government in swaths of England, not to forget Wales and Northern Ireland – while it also risks coming across as arrogant: promising to implement “progressive politics” in the rest of the UK, whether it likes it or not, just as Margaret Thatcher “imposed” rightwing policies on Scotland in the 1980s.
Under current SNP logic, the Iron Lady had a perfect right to do so, for she commanded an overall majority within the “Westminster system”. Funnily enough, nationalists did not defend her governments on that basis at the time. Rather, up went the cry of “no mandate”. Where, then, would the English, Welsh and Northern Irish mandate be for the policies of a party that doesn’t even field candidates outside Scotland?
This is total nonsense. The problem with Thatcher's governments was that they had very little support in Scotland and yet ruled Scotland (in those ancient times before the recreation of the Scottish Parliament, providing the Secretary of State for Scotland was the equivalent of running the Scottish Government). However, even if all the three smaller nations in the UK ganged up together, they'd only have 117 MPs in total (59 Scottish ones, 40 Welsh ones and 18 Northern Irish ones), but a majority in the House of Commons requires 326 seats, so at least 209 English MPs would need to take part, too.
In other words, in the worst case England will be ruled by its second-largest party in a coalition in which at least half the MPs are English. I don't think Scotland would have found such a situation intolerable at all.
What's really happening is of course that English politicians have become so used to the fact that Scotland has almost never made a difference to who governed at Westminster that they think it's undemocratic for the other constituent nations of the UK to exercise real influence.
They should probably have thought of that before they begged us to stay.