© Provided by The iSir Keir Starmer might be living on borrowed time if Labour loses Hartlepool (Photo: PA Wire/Danny Lawson)
Against the backdrop of the grey-brown North Sea, the Headland peninsula at Hartlepool feels like a place on constant alert for the next invasion.
The stone bulwark around a storm-washed former gun battery is lined with memorials to monks and nuns pillaged by the Danes in 640AD and the soldiers killed by a German battlecruiser bombardment in 1914.
But on Thursday it is Labour's turn to try to face down the marauding outsiders threatening Hartlepool's defences - the Conservatives who are throwing everything at a constituency that has been a stronghold in the crumbling "red wall" for more than half a century.
And with one poll suggesting the Tories could be in ahead by as much as 17 points before Thursday's by-election, i discovered a palpable sense of disquiet among the Headland's voters, whose working-class credentials are celebrated with a statue of the comic strip character Andy Capp.
"I've voted Labour all my life," says 74-year-old Roy Carney, a former bus driver who is walking to the shops near the sea wall before the rain comes.
"But for the past 15 years, I've just been disappointed with them. Corbyn was too left wing, but Starmer doesn't know where he's going, so I've decided that I'm not going to vote this time."
Mr Carney adds: "I could never vote for the Tories. I remember what Thatcher did to the pits in the 1980s. I was driving a bus at the time and I saw it. I wouldn't bet on them getting in, but who knows."
Others, though, have already switched long-held allegiances. At Jo's Diner, which is serving homemade curry and chips to facemask-wearing customers, the owner's husband Andy Metcalf is preparing to ditch a lifetime of Labour voting in Thursday's poll, which was called after Hartlepool's former MP Mike Hill resigned.
"I'll be voting Conservative for the first time in my life," Mr Metcalf says with conviction from behind the counter.
"Labour have sucked the life out of this town for years. People have had enough. They've lost my support and I'm not the only one. Let's give the Conservatives a run out. Hopefully, they'll give something back to the North East."
Hartlepool, the port town in which it was said a monkey could be elected if it was wearing a red rosette, has not always taken its elections seriously and voted the football club's mascot H'Angus the Monkey, an independent, as mayor three times from 2002 to 2009.
But it is a sign of the gravity of this campaign, particularly for the fate of Sir Keir Starmer's leadership, that both party leaders have made repeated forays here from London.
Sir Keir made the 522-mile round trip most recently on 1 May to visit a steelworks in support of Labour's candidate and former Stockton South MP Dr Paul Williams.
In a nod to an urban myth which suggested that Hartlepool's former MP, Lord Mandelson, was out of touch because he allegedly mistook mushy peas for guacamole in a local chippy, Boris Johnson spent Bank Holiday Monday meeting voters at a chip shop down the coast in Seaton Carew with his candidate Jill Mortimer.
The wider field of 16 contestants includes another former Labour MP, Thelma Walker, who is standing as an independent but has the backing of the new Northern Independence Party, which is also aiming to put a hole in the "red wall" and claims to be polling in third place.
Carol Hunter, the manager of the Surfside Fish Bar visited by Mr Johnson, which overlooks a beach stained by the black marks of washed up coal, tells i how the Prime Minister greeted surprised customers with elbow bumps.
"I'm not one for politics," she says. "Most people have been Labour here, but he gave the impression he thinks he can win."
Back at the Headland, next to the solid sea wall in between heavy downpours of rain, an ITV film crew can now be found setting up outside a house while making a drama about John Darwin, the Hartlepool "canoe man" who faked his own death to claim life insurance in 2002.
A flotilla of Labour canvassers with red rosettes and clipboards stops to ask the crew if the owner of the house is at home before continuing down the street. "I'm sorry, we're just canvassing at the moment," says one without stopping when he is asked how the election campaign is going.
The pollsters might think it's all over for Labour, but the party can still rely on lifelong supporters like James Gibson. A few streets away from the sea, up the road from a fishing tackle shop with a sign advertising hunting firearms and ammunition, the 66-year-old lifetime Labour voter insists that he is sticking with the party.
"I worked in a steel foundry for 32 years after leaving school at 15," he says. "I'll always remember what the Tories did to us. We're the nitty-gritty working class and that never goes away."