THEY are the party of William Ewart Gladstone and his defining Midlothian Campaign. The party of Henry Campbell-Bannerman and his 1906 landslide victory.

The party of David Lloyd George. The party, too, of Winston Spencer Churchill, in his days as a Dundee MP before he chose, as he put it, to “re-rat” and revert to the Conservatives.

The allied party frequently shaped by Scots: Grimond, Steel, Maclennan, Kennedy, Campbell, Swinson.

They are the party which helped forge the detailed plan for Scotland’s devolved Parliament. The party which governed, in coalition, for Holyrood’s opening two terms. The Scottish party of Bruce, Wallace, Stephen, Scott.

Yet now, as they seek another leader in Scotland, they are a party in trouble. A party in decline, shedding one more seat at the last Holyrood elections from their already minimalist tally. The Liberal Democrats.

In my view, it would be wrong to attribute blame to Willie Rennie, the departing leader of the autonomous Scottish outfit.

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He has served his party well, not least by personally securing a Holyrood victory in North East Fife.

More than that, he has pursued successive SNP First Ministers at Holyrood with diligence and vigour. So much so that Nicola Sturgeon appears to reserve a particular note of contumely for his more persistent contributions, although her comments on his stepping down were gracious.

Further, he has contrived to make a distinctive mark on a series of issues, turning them from generic controversies into topics where the LibDems took the lead. From police restructuring to mental health.

Then there are the photo-calls. Chiefly, the pigs. In the 2016 election campaign, party planners came up with the wizard wheeze of sending Mr Rennie to Gorgie City Farm. He survived an encounter with Dougal the snake. He stumbled in the dung while mucking out the pigsty, still sustaining the trademark grin.

Finally, the interview, as he evinced Liberal principles to camera. The denizens of the pigsty chose that precise moment to copulate enthusiastically in the background. Mr Rennie laughed it off. Eventually.

Yet somehow there is a desperation about it all, an over-modulated yell to be heard, to attract attention, to stave off obscurity and potential oblivion.

I think Willie Rennie has chosen the right time to go. Otherwise, there was a danger it might become evident to some that he was largely retreading previous arguments at Holyrood, pushing treacle up a hill, in Sisyphean style.

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One of his predecessors, Jim (now Lord) Wallace, also stepped down at his peak. He apparently felt it was wise to resign as leader while folk were still asking “why are you going” rather than, in weary fashion, “when are you going?”

But where does the party go now? It seems to be universally accepted that Alex Cole-Hamilton, the Edinburgh Western MSP, will succeed as leader. He may well be unopposed when nominations close. That list is restricted to the tiny band of MSPs, just four in number.

Mr Cole-Hamilton is energetic, diligent and combative. He is a good media performer and commands attention in the chamber. It is thought that he will declare his hand in a fortnight or so, taking the chance then to set out a few ideas for strengthening devolution within the Union.

But can he strengthen an enfeebled party? Most seem optimistic, a habit no doubt inculcated over decades of promise and subsequent decline. One senior player suggested drily that Mr Cole-Hamilton would be wise to surround himself with sensible, wordly advisers who could, if anything, slightly curb his enthusiasm.

There are some grounds for that optimism. At Westminster, the party now has a dozen MPs, including four from Scotland. Ed Davey’s team has been bolstered by the party’s remarkable victory in the Chesham and Amersham by-election.

But such individual victories have come and gone in the past, with little discernible impact on permanent politics.

In the 1980s, it really did look, for a time, as if the political mould would be broken by the combined endeavours of the Liberals and the Social Democratic Party.

That prospect encouraged David Steel to tell Liberals in 1981 to go back to their constituencies and prepare for government. Then there was the Glasgow Hillhead by-election the following year when Roy Jenkins’ SDP victory appeared to confirm an iconoclastic trend, whereby the established structure would be shattered.

Charles Kennedy’s effervescent, if flawed, leadership also raised the possibility, for a brief spell, of a third party surge.

Chesham and Amersham aside, that prospect no longer appears notably salient, despite the travails of the Labour Party. Post Brexit, the LibDems seem to be struggling to find an issue or an agenda to counter the Prime Minister. The most fervent political discourse appears to be within the Tory party.

In Scotland, there is a particular dimension and a particular challenge. The Liberal Democrats are squeezed out of a political debate which oscillates between the staunch Unionism of the Conservatives and the eager advocacy of independence by the SNP.

The LibDems have essayed two strategies. Firstly, disavowing the constitution entirely, arguing that the focus should be upon pandemic recovery. That did not really work because the First Minister is also concentrating on the virus, while the underlying constitutional controversy is still polarised, with minimal room for the LibDems.

Secondly, they talk, sporadically, about federalism. (Similarly squeezed, Labour has occasionally tiptoed down that same track.) It does not work, for either party.

One, nobody grasps what federalism really means. Is it English regionalism: perhaps worthy in itself but no retort to West Lothian? An English sovereign parliament? Too imbalanced.

Two, nobody really cares. Federalism may revive as an issue if and when the pragmatic problems have been addressed. For now, to advocate federalism is to cry in the wind against the stentorian voices of the Union and independence.

Senior LibDem figures insist they will eventually regain popular interest in their fundamental approach; a focus upon the individual, by contrast with what they call “the twin nationalisms” of the SNP and the Tories.

Strategically, a triple approach. Entrench the citadels they hold. Find new, distinctive Scotland-wide issues to pursue. And just keep on fighting in the hope that things change.

Our columns are a platform for writers to express their opinions. They do not necessarily represent the views of The Herald.