Sometimes it takes one small comment to make you look at things in a new light. The BBC news delivered such a comment last night. Fiona Bruce, reporting on the dispute on the timing of a second Scottish independence referendum described Theresa May and Nicola Sturgeon as 'the two most powerful politcians in the UK'.

I trust I will be forgiven for recoiling slightly but a lifetime of political interest has led me to think that such a description would be given to the prime minister and one of the chancellor or the leader of the opposition. But it only takes a moment of reflection to realise that all has changed. No one would have called Donald Dewar the second most powerful politician in the UK. Nor, candidly, would that title have gone to Alex Salmond when he was First Minister. But Nicola Sturgeon? Yes, she does deserve the title.

You could argue that this is because she is up against such weak opposition. Philip Hammond was never a towering figure. As of this week he is a diminished one heading for retirement and not of his own volition. And then there is Jeremy Corbyn. I presume some of his followers still think he has a role. But he is so far from being a powerful politician it is an embarrassment to almost list him as being in contention for the title.

But that's not why Nicola Sturgeon has undoubtedly earned the title. She's there because she stands head and shoulders above all else in the field. Partly that's because she leads a pretty united party in a parliament that seems to go about its business in a much better way than Westminster. And it's because her team at Westminster are, without doubt, the most able group in parliament, partly because almost all of them have real world experience way beyond the political sphere, which is now so rare elsewhere. And they use that skill extremely effectively.

But mainly Sturgeon wins because of her coherence. She knows what she's for. No one can doubt it. And whilst she is frustrated in delivering much that she'd like (Scottish government has been set up as a poisoned chalice by successive Westminster leaderships, and most especially those since 2010) there is no doubt that she unites her team around a passion. Most in England have little comprehension of Scottish nationalism, just as they did not of Irish nationalism before it. And they deeply resent it: I have been told, often, that Scots should be grateful for the privilege of being in the Union. But that, of course, is exactly why it works in Scotland. And it is what drives Sturgeon to deliver a vision that in many ways makes her the most powerful politician in the UK.

I say that because May is so weak. No one believes her support for hard Brexit is anything but cynical. Less than a year ago she was saying it would be a disaster. And no one believes she really cares about most people in the UK or their issues: if she did we would not be seeing the massive cuts in disability benefits now going ahead. What is more, no one, after the last couple of weeks, can believe in her competence. And it looks like she is in power only because of what may well prove to be criminal dishonesty in her party. She's so toxic that if the Scots (because this requires more than the SNP) force a referendum sooner rather than later the defence of the Union could not fall to May, because she would surely lose it, but to Ruth Davidson, who is the last single hope the Unionists have. That's how diminished May is.

In that case, and given that the future of the UK is in doubt, the question of who the two most powerful politicians in the UK might be is clearly answered by May and Sturgeon. But if you asked who is the most powerful, and wholly appropriately considered that answer in the context of whether or not there is a Union, then May might come second.

That's telling. For the Union, For the sorry state of English and Welsh politics. And for the future identity of the people of this island which is very definitely not one country.