In his new book, “The End of British Party Politics?”, the political scientist Roger Awan-Scully captures the paradox of last year’s general election in Scotland.

While the Unionist parties successfully played on the SNP’s “turf” of weaponising Scotland’s constitutional future, in doing so “they further distanced Scottish political debate from that in the rest of the kingdom they earnestly wish Scotland to remain a part of”.

Indeed, for the first time in a UK electoral contest, 2017 produced a different victor in each of the four home nations, Labour in Wales, the Tories in England, the SNP in Scotland and the DUP in Northern Ireland. British party politics is dead, long live sub-national contests.

Iain Macwhirter: The horror, the horror - Brexit, one year to go

This tension is most acute in the only party with “Unionist” in its name – the Scottish Tories. For more than a century, it has had to be simultaneously Scottish and British, both “standing up for Scotland” and preserving the Union of which it is a part. Such an approach can pay dividends, but it can also cause problems.

Take two prominent rows since the 2017 election. First was the billion-pound “bung” to Northern Ireland in return for propping up Theresa May’s minority government, second was the more recent row over the Conservatives “selling out” Scotland’s fishing industry (such as it is) in agreeing a transitionary arrangement with the European Union.

In both cases, the SNP claimed Ruth Davidson had failed in her aim of “standing up for Scotland” from within the United Kingdom, for in the first case she’d failed to secure equivalent funding for Scotland, while in the second she had reneged on a promise Scottish fishermen wouldn’t be subject to the Common Fisheries Policy (CFP) beyond “independence day” on 29 March 2019.

To a degree, the Scottish Tories only had themselves to blame: not only had Scottish Secretary David Mundell bought into a bogus narrative which completely misunderstood how the Barnett Formula actually worked, but Davidson also overstated what might be possible when it came to exiting the CFP. With both incidents, however, the facts mattered less than the perception.

Iain Macwhirter: The horror, the horror - Brexit, one year to go

If you promise to “stand up for Scotland” then at some point you’ll need to produce results, which so far amount to some goodies in Philip Hammond’s most recent Budget. This is important, for Ruth Davidson’s “nationalist unionist” pitch is an important element of her aspiration, as she puts it in a new collection of Scottish Tory essays, “to lead the next government of Scotland”.

It’s clear from the contributions that follow – more personal reflections than detailed policy – that the party realises this can’t be done from the Right. Policy chief and MSP Donald Cameron champions government as “a means, not an end” and promises a vision for “a liberal, confident Scotland…a vision avowedly of the centre, not of extremes”.

His colleague Adam Tomkins also writes on “tackling the causes of poverty and social justice”, which includes a brave attempt to claim Darren McGarvey (aka Loki) as a modern conservative for rejecting left-wing orthodoxy that “individual behaviour” has nothing to do with poverty (though Tomkins is also careful to reject the opposite “deeply ill-informed” contention that poverty “has nothing to do with the structure of the economy”). This is Scottish Conservatism, Jim, but not as we know it.

Some of it’s a bit muddled, such as Ruth Davidson’s goal (shared by Mrs May and Nicola Sturgeon) of making Scotland “a genuine meritocracy”, which fails to appreciate that the late Michael Young meant “The Rise of the Meritocracy” as a warning, not an aspiration. Nevertheless, the publication reveals a party more confident in its history, role and traditions, a far cry from the defensive, hollowed-out shell I remember from 20 years ago.

But does this add up to victory in the 2021 Holyrood election? When pushed on this point, Scottish Tory MSPs usually point out that the SNP went from 27 MSPs in 2003 to a minority government four years later. This is true, but the Nationalists did that with a 33 per cent vote share – the Conservatives managed just 22 per cent in 2016 and 28.6 per cent in last year’s general election.

Here, then, is the best-case scenario for 2021: a three-way split (between the SNP, Labour and Tories) in which the Conservatives poll in the low 30s and emerge as the biggest party – just – much like the SNP in 2007. A lot depends upon Brexit which, as the CFP row demonstrates, isn’t necessarily good for the party in Scotland. On the other hand, Davidson’s poll ratings remain strong, and it’s widely assumed Sturgeon will struggle to keep the SNP brand fresh after 14 years in devolved government.

But, and there are several buts, even if the Scottish Tories do emerge as the largest party it’ll need a credible number of seats to form a minority administration (in 2007 the SNP had 47). Labour and the SNP might also form an anti-Tory pact to keep Davidson from becoming First Minister. Under another scenario, meanwhile, the Conservatives don’t even get that far.

Iain Macwhirter: The horror, the horror - Brexit, one year to go

Many are conscious of an electoral “glass ceiling” and, ironically, one brake on further advance is what one MSP refers to as “the Westminster link”. “If we’re going to attract centre-right Nats in serious numbers”, he reflects, “we can’t do that while tied to Boris & co.” It’s that paradox again, a Unionist party complaining of unhelpful English colleagues.

If, then, the Scottish Tories find themselves instead facing another term in opposition, Ruth Davidson might head south ahead of the 2022 UK general election. She will, after all, have been leader for almost a decade, but if she does, then much of her party’s progress since 2016 risks being lost. Who’ll be left standing up for Scotland then?