In a by-election in the birthplace of the comedian Tommy Cooper, it was Plaid Cymru that had the last laugh.

During the campaign, Nigel Farage and Reform UK’s candidate Llyr Powell had posed for photos in front of the statue of the legendary comic in Caerphilly.

But when the result was declared at 2.10am at the count in the town’s leisure centre, Mr Farage – who’d been campaigning for Mr Powell on polling day – was nowhere to be seen.

In fact, the joke among Plaid supporters at the count was that Mr Farage was halfway down the M4 on his way back to London – long before the declaration.

It was one of those by-election counts when one party – in this case Reform UK – is expected to win as the polls close at 10pm, but within a few hours it becomes clear the other party looks like winning.

After all, Reform UK threw everything at the campaign, Mr Farage had visited three times and a poll last week had suggested his party was ahead of Plaid Cymru by 42% to 38%.

Plaid’s by-election winner Lindsay Whittle, a cheerful extrovert dressed in a colourful crimson jacket, admitted in a Sky News interview that he’d fought parliamentary and Senedd elections in Caerphilly unsuccessfully 13 times previously.

If at first you don’t succeed…

He was chipper from the moment he arrived at the count even before the polls closed, and was clearly pretty confident he was going to win.

Contrast his body language with the forlorn figure of Mr Powell, who without Mr Farage or Reform UK’s Zia Yusuf – who’d been at the count for an hour or so at the beginning but had left – appeared to arrive on his own and looked neglected by his party as well as dejected.

As runner up, poor Mr Powell had the opportunity to make a speech after the declaration but chose not to, though some of the other losing candidates did.

This result is a huge boost for Plaid, however, as the party aims to seize control of the Senedd in elections next year. But it’s a big setback for Mr Farage’s hopes of making inroads in Wales.

But for Labour, whose vote crumbled like Caerphilly cheese, it’s a disaster and will send many Labour MPs into a panic about their chances of holding their seat at the next general election.

In the end, for all the talk of the result being close, it was a relatively comfortable win for Plaid, with a majority of nearly 4,000.

In his Sky News interview, Labour’s Huw Irranca-Davies, a former Westminster MP who’s now deputy first minister in Wales, blamed Reform for cranking up immigration as an issue in the campaign for Labour’s slump in support.

But this result shows that it isn’t only Reform that poses a threat to Labour, but also parties on the left such as the nationalists.

Caerphilly has sent Labour MPs to Westminster for more than a century and Labour Welsh assembly and Senedd members to Cardiff since devolution began in 1999.

This was a Labour stronghold as impregnable as Caerphilly’s mighty castle. Not any more though, it seems.

The result will serve as a warning that Labour’s dominance in the valleys and what might be described as “old industrial Wales” may be coming to an end.

And just like a Tommy Cooper magic trick that goes wrong, that could happen just like that.