Could Caerphilly see historic by-election on Thursday?

Caerphilly's by-election takes place on Thursday, following the sudden death of Labour MS Hefin David

This is a Labour stronghold.

The party has won every election here in Westminster or the Senedd for more than 100 years.

But right from the beginning of this by-election campaign sources within Labour have been realistic about their chances.

It is that potential for a historic change, so close to next May's Senedd election, that makes Thursday so fascinating and potentially so significant.

The first minister told the recent Labour conference that the party faces a "hell of a fight" to hold on to power next year.

Historian Elin Jones, who has lived in the area all her life, told BBC Wales that Thursday's poll and next May's election could be hugely significant for Labour.

Caerphilly is "one of those places where you felt it will never change much, and I have seen it change very suddenly", she said.

"This by-election, I think, is going to show that after a century the Labour Party has lost its grip on this area and perhaps its grip on the whole of Wales."

So why are expectations for Labour lower than you might expect in one of its heartlands?

Well, the party has been in power for 26 years in Cardiff Bay and there are question marks over its record on the NHS and education - and spending priorities on things like the 20mph law and an expanded Senedd.

Last year the Welsh party almost tore itself apart with the row over donations to former first minister Vaughan Gething's leadership campaign and his eventual resignation.

Despite only being back in power for 15 months at Westminster, polls also suggest that the UK Labour government and Keir Starmer are unpopular.

First Minister Eluned Morgan did not use the phrase "hell of a fight" lightly, and she will also be aware that after 26 years some voters might simply want a change.

She has tried to strike a tricky balance – trying to differentiate the Welsh party from UK Labour, while also welcoming more than a billion pounds of extra funding from Westminster, which has been used to tackle NHS waiting lists.

Manager Rachel says no politicians have come to her café to 'tout their wares'

As polling day approaches in Caerphilly locals in the Old Library Coffee Shop, in the shadow of the town's castle, have been digesting the past few weeks.

The campaign appears to have been either front and centre of local life, or very quiet, depending on who you speak to.

Lyn told me that she had found it "quite intrusive".

"I have had people knocking on my door morning, afternoon and evening," she said, adding later that "we know what will happen when it's over" - suggesting that the politicians would "disappear".

Café manager Rachel has had a very different experience.

"I haven't seen any politicians canvassing," she said.

"I would have thought they'd be out in force. Nobody's coming here. We're a local business, but no one is coming here to tout their wares."

Although big picture issues like immigration, the NHS and trust in politicians have featured in many of the public exchanges, there has also been a sharp focus on local worries.

Cliff, enjoying a cuppa alongside Lyn, brought up the decision by the Labour-run local council - blocked by a court order - to close libraries.

Labour's by-election campaign to keep them open has led to accusations of hypocrisy from some opponents.

"People see the library not only as a place to borrow books but also to socialise as well, especially elderly people who go to the swimming pools as well," said Cliff.

Anne said that the biggest local issue was transport.

"There is hardly any transport here, the buses have recently been stopped going across the mountain into Cardiff and they go as far as Heath Hospital, not as far as Cardiff centre which is where most people want to go," she said.

Cliff is concerned about the future of local libraries

Opposition parties sense their chance in Caerphilly and in 2026.

Both Nigel Farage from Reform and Plaid Cymru leader Rhun ap Iorwerth have visited the constituency, as has Senedd Tory leader Darren Millar and Morgan.

The stakes are even higher on Thursday because of the Welsh government's budget.

A Labour defeat would mean it could no longer rely on the sole Liberal Democrat Jane Dodds to help pass its spending plans as it did this year.

Millar has already met Morgan for talks and Dodds is also understood to have met finance secretary Mark Drakeford.

This has been a heated campaign at times.

Six of the candidates spent large parts of last week's live BBC debate shouting at each other.

This could be a foretaste of what to expect next year.

Plaid Cymru and Reform have been keen to portray themselves as the only viable alternative to Labour.

The Welsh Tories have presented themselves as the only credible party of change, having never been in government in Cardiff Bay.

For the Lib Dems, Greens and others the new 2026 system of proportional representation arguably gives them a better chance of boosting their numbers or returning a Member of the Senedd (MS) for the first time.

However the Caerphilly by-election turns out on Thursday night, it will be just the start of six potentially era-defining months before that big Welsh election next May.

Who is standing in the by-election?

The full list of candidates for the Caerphilly by-election is:

• Liberal Democrats: Steve Aicheler

• Gwlad: Anthony Cook

• Greens: Gareth Hughes

• Conservatives: Gareth Potter

• Reform: Llyr Powell

• UKIP: Roger Quilliam

• Labour: Richard Tunnicliffe

• Plaid Cymru: Lindsay Whittle

Find out more about the candidates here.