Unlike her predecessor as leader of the Scottish Tories, Ruth Davidson is a household name throughout the whole of the UK. Under her leadership, the Conservatives in Scotland have, finally, started to win seats, both at Westminster (remember the Tory wipeout in 1997, when they were left without a single MP north of the border?) and at Holyrood. She's young, she's out and proud, she's a Christian, she's from a working class background, she's an ex-military kickboxer.

She's also feisty and jolly and not afraid of speaking her mind – and already seen as a potential leader for the Conservatives throughout Britain, should she want the job. What kind of a person is she, and how has she achieved so much?

Before we get to that, though, she provokes a further question – why is she a Conservative? She once said before an election: 'I'm voting for a break for low-paid workers. I'm voting for schools that end inequality. I'm voting for more nurses in our hospitals. I'm voting for a local police force...' Yet, at that point, the Conservative austerity programme was still in full swing. How does she reconcile herself to that? Surely her kind of Conservativism, in which dedication to protecting the NHS in particular and supporting social justice in general, is no longer the kind that prevails in Westminster – if it ever did? And how did she manage to generate enough support, in a country where the Conservatives were loathed, to become effectively the leader of the opposition in the Holyrood Parliament, and to have more Scottish MPs in Westminster than Labour do, for the first time since 1959?

It was with this background of questions that I read Andrew Liddle's book, Ruth Davidson and the Resurgence of the Scottish Tories. Liddle is a good biographer and political writer, and he weaves her story around the story of the Conservatives in Scotland. Conservative support in Scotland was once a very powerful force. It had begun to decline before Mrs Thatcher decided to trial the Poll Tax there. In fact, 1997 was not their lowest point – the book charts their fall to an even smaller percentage of the vote in the first elections for the Scottish Parliament, where they gained a miserable 15.5 per cent.

Only the fact that the Scottish Parliament has a form of proportional representation meant that there were actual Conservative MPs elected. So the road back to electoral success of any kind has been long and hard, and Liddle charts it in detail – I found myself Googling the actual results, to see a clearer picture of the recovery.

One key issue that he brings out is that Thatcher seemed to represent a disdainful attitude towards Scotland, in which Scottish interests were not even worth considering. Cameron did little to dispel this, but Ruth Davidson is, clearly, pro-Scotland. Her vision for Scotland differs from Nicola Sturgeon's, but it is nevertheless genuine and heartfelt. Nor does it appear that, for Davidson, Holyrood is just a staging post in a career whose ultimate aim is Westminster. She's not there in Holyrood just to bide time before aiming at her real goal.

Ruth Davidson is different from most Conservative leaders and this might have been why she was chosen. After all, clearly the party had to do something different, as doing more of the same would result in the same poor showing. She stood out – she would do so in almost any party, but perhaps most of all in the Conservatives. Not that she has had an easy time as leader. She was emphatically not what many Conservatives in Scotland either wanted or expected. She had a hard fight, both within the party and at each election, to keep going, and she comes across in the book as admirable in her determination, her honesty and her humanity.

We now see her as the darling of the Conservatives, north and south, but in fact when she first became leader – having only just become a Member of the Scottish Parliament – she was resented. Those asked to meet with her would not turn up. There was, Liddle seems to be saying, a strong tradition of 'Buggins' turn' – that those who served the Scottish Conservative party loyally would eventually be rewarded by being put forward for election. Davidson stopped all that, insisting on a rigorous selection system that meant only those who met certain criteria were able to stand. This of course has brought her more enemies: it has also resulted in a new generation of politicians who owe their political loyalty to her, and were she to travel south, applying the same rigour to Conservative politicians at Westminster might result in some interesting by-elections (though it is doubtful that existing MPs would be de-selected).

There are other questions. She is said to be concerned about issues of social justice (as indeed is Theresa May) but, when questioned about the bedroom tax, Davidson apparently just shrugged. Are her principles perhaps not as important as we might hope? Liddle also questions the wisdom of a comment she made about Donald Trump, when she said 'I would back almost anyone over Donald Trump' – but then there comes a point, perhaps, when diplomacy should give way to honesty, to prevent certain kinds of behaviour from being seen as acceptable, if practised by the sufficiently powerful.

Speaking her mind has, perhaps, not always been wise politically – she had to rebuild her relationship with Boris Johnson, and she also once accused Andrea Leadsom of telling a 'blatant untruth'. But this is where her appeal lies. In an age when authenticity is so valued, Davidson seems to combine both honesty and appeal – she is herself, and we like the Ruth Davidson that we see.

Might she become leader overall of the Conservative Party in this country? Despite her reservations, she might one day be persuaded that this is where her duty lies – and ideas of duty still ring true with Davidson. Certainly, she is worth watching – and the book is definitely worth a read.

Andrew Liddle's 'Ruth Davidson and the Resurgence of the Scottish Tories' is published by Biteback.

Ali Hull is a freelance commissioning editor and book reviewer, and has spent more than 20 years working with books and authors.