The Hartlepool by-election is a Brexit story.

Britain's Conservative Party has taken the constituency for the first time since it was created almost 50 years ago.

This constituency voted heavily for Brexit in the 2016 referendum – 69%, compared with the national vote of 52% in favour.

In the 2019 General Election, it was the place where the Brexit Party came closest to winning a seat. Party Chairman Richard Tice chose it as the place to make his stand. He pulled in 26% of the vote – not bad for a wealthy businessman in a post-industrial coastal town in the northeast of England.

But Brexit is a powerful force, certainly in Hartlepool.

The Labour candidate in 2019 won the seat with 38%, and the Conservatives got 29%.

That was the Brexit election, the one that gave Boris Johnson his "stonking great majority" in support of his "oven ready" Brexit deal (Northern Ireland protocol and all). So when that majority passed the Brexit withdrawal agreement a few weeks later, it brought a natural end to the Brexit party, which has lost its raison d'etre.

With no Brexit Party this time, the question was always going to be where are those pro-Brexit votes going to go? For the Conservatives, the party that delivered Brexit, the answer was obvious – "they are going to go to us".

Prime Minister Boris Johnson campaigning with Conservative Party candidate Jill Mortimer in Hartlepool

That's why Boris Johnson visited the constituency three times during the campaign – that’s three visits more than he paid to the whole of Scotland during the same campaign period.

Labour may have undermined itself in its choice of candidate. Dr Paul Williams had lost his seat in another constituency in the 2019 election. He was an ardent remainer, someone who wanted the UK to stay part of the European Union. The Tories saw this as a weakness in a very pro-Brexit constituency, and set about exploiting it.

And that meant bigging up Boris Johnson. Not only was he the Prime Minister who had delivered Brexit, but he was also the Prime Minster who had delivered the fastest vaccine roll-out of any major country. And the party and government had been saying for months it could not have been done if the UK was part of the EU. This was a clear Brexit dividend for the people. A poll at the start of April indicated the Conservatives could win the seat, and the party piled in resources.

Clearly Brexit had become a big issue in this constituency.

But there was no certainty they would win those loose Brexit party votes. Back in the 2017 General Election (Theresa May's snap poll to get a mandate for Brexit that instead left her reliant on the DUP), the UKIP vote - for that was their name then - slumped by about 4,000, while the Labour vote went up by even more, leaving its candidate topping the poll with a 52% share. The Conservative vote went up as well, leaving them in second place with 34% compared with UKIP's 11.5%.

But that was after the referendum. The expectation among Brexit supporters was that the government would deliver what they had voted for – emphatically voted for in the case of Hartlepool. Remember, 69% voted for Brexit in the 2016 referendum in that constituency.

The year before, in the 2015 General Election, UKIP delivered a shock to the Tories, pushing them into third place. While Labour won, as usual, it was with 35%, UKIP got 28% and the Tories 20%.

Clearly Brexit had become a big issue in this constituency. In 2005, UKIP had scored 3.5%, in the 2010 General Election it had doubled that to 7%. Then a fourfold boost to 28% in 2015. In between those two elections was the financial crisis, and a lot of austerity budgeting by the Conservatives. Then came the referendum.

Former Northern Ireland Secretary Peter Mandelson recorded Labour's biggest win in Hartlepool in 1997

So in the past three general elections, the Labour majority was 3,000, then 7,000, then 3,000 again. And the waxing and waning of the Brexit Party/UKIP accounted for the volatility. Now, with The Conservatives as the only "Brexit" party in the race, the planets had aligned for Labour's eclipse.

Hartlepool has been a Labour stronghold since it was first carved out as a constituency in 1974. Labour MP Edward Leadbitter first held the seat from 1974 to 1992 before Peter Mandelson, a key figure in the New Labour movement, was parachuted in in the early 90s. He delivered Labour’s biggest win here – a 60% share in the 1997 Labour landslide that brought Tony Blair to power. Mandelson later became Northern Ireland Secretary, and then EU trade Commissioner in 2004, which triggered a by-election.

Iain Wright (the MP; not the footballer) won the by-election that year, holding the seat until he quit in 2017. But UKIP scored 10% in that election, just shading it over the Tories – and this at a time when the Blair government was becoming unpopular.

As American political operatives like to say, when you are explaining, you are losing.

Most recently, Mike Hill had represented Hartlepool in the Houses of Parliament from then until March 2021, when he resigned after facing sexual harassment claims – which he denies. This year's Labour candidate, Dr Williams, a local NHS employee, was also criticised by Tory MPs for his alleged role in removing services from Hartlepool hospital in 2013. Although the doctor rejected these criticisms when speaking with the Hartlepool Mail recently, blaming government cutbacks.

"The Tories cut funding to the NHS and at the time I was trying to get the best possible deal for my patients", he said. "It was the only decision because of Tory funding cuts to the NHS, the only safe decision for Hartlepool patients, but we’ll get those services back," he told the paper.

But as American political operatives like to say, when you are explaining, you are losing.

Trying to fight on the slippery terrain of the local hospital is always hard (ask any politician anywhere). Trying to do so whilst dodging the rounds from a big bazooka marked Brexit proved impossible for Dr Williams.

This is just one Parliamentary by-election, a snapshot of a particular time in a particular place. But it will be used ruthlessly by the Conservatives to beat up Kier Starmer and the Labour Party. Expect similar tactics to be employed anywhere else in England the Conservative party think there is the slightest sniff of a win. In other words, north of England seats where there was a big pro-Brexit vote in the referendum, and a significant UKIP/Brexit Party vote too.

Where those target seats may be should become clearer over the coming days, as local election results in various parts of England trickle in. But nearby areas in the northeast, such as Durham and Sunderland will be closely watched.