Winner in 2019: Christine Jardine (Liberal Democrats)

THE recent history of the Edinburgh West constituency, and probably the immediate future too, is a small tragedy in its own way.

It's a story not only of the worst effects of the first-past-the-post voting system, but also of how a political party that was once defined by principled opposition to that system has now become enslaved by it far more than any other party in Scotland.

Edinburgh West was a reliable Tory heartland until the Liberal Party nearly won in 1983. That result was used to convince many Labour and SNP supporters in subsequent elections that the only effective way of resisting Thatcherism in the constituency was a Liberal vote.

Two further near misses followed in 1987 and 1992, until at last the Tories were defeated by the post-merger Liberal Democrats in 1997. And initially, the discipline of tactical anti-Tory voters was well-rewarded, because the incoming Lib Dem MP Donald Gorrie represented a genuine alternative to the Conservatives.

READ MORE: Does this Scottish constituency mirror the views of nation?

He was from his party's radical progressive wing and also its 'soft nationalist' tendency - defined more by support for Home Rule than by opposition to independence.

But a generation later, the political tradition Gorrie belonged to barely seems to even exist within the Lib Dems anymore. And the paradox is that it was indirectly destroyed, at least in part, by his own breakthrough in Edinburgh West.

After the Lib Dems were almost wiped out in Scotland in the post-indyref SNP landslide of 2015, they faced a strategic choice - they could either try to build up broad-based national support for a liberal option that transcended the constitutional divide, or they could draw circles around a handful of small areas, such as Edinburgh West, where by reinventing themselves as a hardline British Nationalist party, they might be able to exploit the voting system and use their small pockets of support to persuade unionists to vote tactically for them to keep the SNP out.

They plumped for the latter option, which meant that practically overnight, they went from being Edinburgh West's "Not The Tory Party" to being the constituency's "Not The SNP Party".

And it worked - other than the brief period between 2015 and 2017 when the SNP's Michelle Thomson held the seat, the Lib Dems have kept on winning. But it's come at a heavy price, because the party they've had to become to hold seats like Edinburgh West is not particularly attractive to voters outside the handful of Lib Dem enclaves.

Even within Edinburgh West, there are voters who backed Gorrie in 1997 and are bemused that the effect of their votes was to build up a political force which is now a vehicle for small 'c' conservatives who oppose Scottish self-government.

Many of those disillusioned former Lib Dem voters are now firmly in the SNP column.

Having effectively replaced the Lib Dems as the constituency's main party of progressivism, the SNP has been able to maintain healthy local levels of support.

And with a small part of the SNP-held Edinburgh North and Leith seat having now been transferred to the constituency, they start a mere four points behind the Lib Dems in the notional 2019 results.

But the problem is that there is still a substantial 18% Tory vote share from 2019 that the Lib Dems may yet squeeze. The 2021 Scottish Parliament result offered a preview of what will happen if those Tory votes move abruptly in one direction.

The Scottish Lib Dem leader Alex Cole-Hamilton (below) increased his majority over the SNP in the equivalent Holyrood constituency of Edinburgh Western from less than 3000 votes to almost 10,000, even though the SNP vote share remained roughly static.

(Image: PA)

That happened because the Tory vote plummeted from 14% to 6%, with Cole-Hamilton essentially the sole beneficiary.

Now the Conservatives are stuck in a trough of unpopularity, it's likely that many Tory voters in Edinburgh West will be looking for a new home.

If they travel in the same direction as in 2021, the incumbent Lib Dem MP Christine Jardine may surge beyond the SNP's reach.

The realistic target for the SNP candidate Euan Hyslop will perhaps not be to win, but to retain a big enough vote share to keep his party in contention for future elections held in more favourable circumstances.