Eight years is a long time nowadays to lead a Party in Opposition. It used to be different before the round-the-clock demands of the media became so pressing. Ruth Davidson has been leader of the Scottish Conservative 7 Unionist Party since 2011. Now, with a baby not yet a year old, she has resigned and also said she will leave the Scottish Parliament at the next election in 2021.

Her time as Leader has seen a revival in Tory fortunes, for which she has been principally responsible. The Tories are now the chief Opposition Party in the Scottish Parliament where Ruth has been an effective critic of the First Minister, Nicola Sturgeon. The Party has, for the first time in two generations a respectable representation at Westminster. Without Ruth’s energetic leadership of the Scottish Party  it is unlikely that Mrs May would have had a majority; nor, ironically, would Boris Johnson now. I say “ironically” because Ruth has had little time for Johnson. They clashed during the European election and Ruth had the better of Johnson in a TV debate. Pointedly she didn’t invite him to this year’s Scottish Party Conference, and she made it clear that she didn’t support his leadership bid.

He had his revenge at once, dismissing Ruth’s friend and ally, David Mundell, and replacing him as Secretary of State for Scotland by a Brexiteer, Alister Jack. I think she might have gone anyway, but this choice made Johnson’s indifference to the 62-38 Scottish majority in favour of Remain abundantly clear.

The future for the Scottish Tories now looks bleak. It is not just that they will miss Ruth’s energy as a campaigner; they will be deprived of her ability to appeal to people who had never voted Tory before. Some of them won’t do so again. They were Ruth voters rather than Tory voters. If there’s a General Election this autumn, the Tories will lose seats in Scotland. Pessimists think they may hold two, optimists four or five.

The truth is, however, that since the EU referendum Ruth has found herself boxed into a corner. She is a Unionist who campaigned vigorously and, in Scotland, effectively, for Remain, but in the other Union she supports there was a clear, if narrow, majority for Leave. Now, Alister Jack, Scotland’s man in the Cabinet and Johnson’s man in Scotland, enthusiastically supports what Scotland, and probably a majority of those who voted Tory in the last two General Elections, rejected.

A second Scottish Independence referendum is likely at some point in the next two or three years – not certain but likely. In 2015 the No to Independence campaign was led in Scotland by Labour heavyweights, notably Alastair Darling and in his late decisive intervention, Gordon Brown. Ruth was the only persuasive Scottish Tory. Given the enfeebled state of the Scottish Labour party today, she would have been the natural leader of the next campaign in defence of the Union. One can’t see anyone capable of replacing her. Assuming Johnson is still Prime Minister any Tory associated with him starts in Scotland as damaged goods. There are no heavyweights in Scottish Labour now and Johnson’s man in Scotland, Alister Jack, has as much weight as a puffball.

Nothing of course is certain in this crazy world. It’s possible that Ruth has taken the Tories in Scotland as far as they can be taken. On the other hand events may change opinions and loyalties. Johnson may yet get an acceptable deal in negotiations with the EU and persuade a weary, if still angry and resentful, Parliament to approve it. The outcome of a No Deal departure might prove less awful than feared. Events in Scotland may disrupt the SNP and weaken Nicola Sturgeon’s position, even – just conceivably – forcing her out of office. Less dramatically the polls may simply shift again in favour of the Union and against Independence.

One can’t tell. Predictions in the present fevered atmosphere are a mug’s game. One may with some assurance say that Ruth’s departure weakens the Scottish Tories immediately and is likely to make a defence of the Union more difficult.Yet, even as one says this, one remembers that when she became,  leader in 2011, few predicted she would be the success she has proved to be. Her rival in that Party contest, Murdo Fraser, argued that the Scottish Tories should break away from the UK party in order better to establish their distinct and independent identity. Given Johnson’s unpopularity in Scotland that argument may resurface: better a lifeboat than drowning at sea.

All is in flux, but one of the few things one can immediately say is that Ruth’s departure is bad news for the Tories and not at all bad news for the SNP.