CHARLES Kennedy once observed that to be a Liberal Democrat was to be “an eternal optimist”.

That optimism was borne out yesterday with the shock by-election win for the Liberal Democrats in Richmond Park, that saw challenger Sarah Olney overturn ex-Tory MP Zac Goldsmith’s 23,015 majority. According to LibDem leader Tim Farron, this means his party is “back in the big time”, a result that doubtless justifies the Li Dems throwing everything, including a guest appearance by pop star and campaigner Bob Geldof, into their campaign to secure victory in southwest London.

Adamant as Mr Farron is that the Richmond result is the “beginning of something special,” it is worth bearing in mind that over the last few decades, the LibDems appear to have hailed more new dawns than the planet Jupiter. Let us not forget that up until yesterday their elections results of late have been woeful. In 2014 they lost all but one of their 11 MEPs, then last year lost 49 of their 57 MPs at the General Election, and this year dropped into fifth place at Holyrood behind the Greens.

Given such a track record, one could be forgiven for allowing Mr Farron the indulgence of yesterday’s celebration and as one reporter put it, his “jumping around Richmond Park like a gazelle”. Once over the initial euphoria, the party will still face the stark reality that one swallow does not a summer make, and the LibDem force at Westminster, though now enlarged, still numbers a meagre nine MPs.

In Richmond the party claimed it had turned the contest from one about Heathrow expansion into one about Brexit. Mr Farron said the result was a verdict on Theresa May’s “Ukip-ish” take on Brexit and insisted too that Ms Olney’s victory sent a clear message that in the face of the Brexit and Trump victories people were prepared to turn once again to a moderate, progressive liberal force.

For her part Ms Olney said the victory now gave her a mandate to vote against the Article 50 process for triggering Britain’s exit from the EU.

This last point is of some significance given that one effect of the by-election has been to reduce the Tories’ working majority to just 13.

The bottom line here is that numbers matter. Given the possibility of a vote on the UK Government’s Brexit strategy in the New Year the Prime Minister might face nervous times ahead and can ill-afford to keep losing by-elections.

Not that the lady and her government were for turning yesterday. Richmond will however give the PM some real food for thought and focus the minds too of those looking on from Europe.

Meanwhile, spare a thought, albeit briefly, for Zac Goldsmith, Tory loser in Richmond. Scion of the Goldsmith dynasty, he also lost the London mayoral election earlier this year, and last month saw Theresa May rip up David Cameron’s previous pledge of “no ifs, no buts, no third runway”.

Now he is no longer an MP. Unlike others made redundant though, his livelihood is assured. The comfort of a golden inheritance to fall back on courtesy of his late billionaire father Sir James will see to that.