If the ancient wood-panelled walls of the Crown and Treaty in Uxbridge could talk, they would speak to the perils of crossing parliament.

In the heart of Boris Johnson’s west London constituency, this former manor house hosted talks over the ill-fated treaty of Uxbridge in 1645, an abortive attempt to end the first English civil war, which arose from a battle between parliament and the executive and ultimately led to Charles I losing his head.

Now the recently restored gastropub is about to bear witness to the consequences of another parliamentary fight: a general election with the possible prospect of a serving prime minister losing his seat.

“I think the youth vote will go against him and I think he’s got a battle on his hands,” said MaryJane Prendergast-Lister, 18, who works at the Crown and Treaty and will be a first-time voter.

She said the focus would be on Brexit. For those her age, “this is their first opportunity to have their say, though maybe there’s no point now,” she said, dressed up for Halloween on the day Johnson had pledged that the UK would leave the EU.

Facebook Twitter Pinterest MaryJane Prendergast-Lister: ‘I think the youth vote will go against him.’ Photograph: Susannah Ireland/Guardian

The pub’s deputy manager, Sophie Girard, 27, agreed. She is French, though she was born in the UK. She returned to the UK 12 years ago and now finds herself having to apply for residency, which she said was “absurd” and “something I didn’t think was necessary up until the result came in on [referendum] day”. Her British friends all voted remain. “They think the election will be all about Brexit, and so do I,” she said.

Taking on Johnson in Uxbridge and South Ruislip will be Labour’s Ali Milani, 25. He may not have Johnson’s recognition factor on Uxbridge high street, but on the campus of nearby Brunel University, his alma mater, he is well known. Mobilising the student vote is crucial if he is to topple Johnson, whose majority was halved in 2017 to just 5,034, now the smallest of any prime minister since 1924.

Johnson’s seat is on an internal CCHQ list as potentially at risk. There have been rumours he might relocate to a safer one.

Milani requires a swing of just over 5%. He is the antithesis of Johnson. An Iranian immigrant who moved to a Wembley council estate with his mother and sister when he was five, he studied politics at Brunel, where he was the student union president before becoming a vice-president of the National Union of Students. A practising Muslim, he attends Friday prayers on Brunel’s campus, and he pitches himself as the “local candidate”.

Play Video 5:35 Will this young Muslim be Boris Johnson's ultimate downfall? – video

“I’ve studied here, I’ve worked here, I live here. I had surgery in the local hospital. I tell them on the doorstep: when Boris Johnson is ill, which hospital do you think he will be treated at?” he said.

“[Johnson] has no connections to this area other than as a platform for him to get to No 10. At the time it was a safe seat for him, though not any more.”

Milani believes no single issue will determine the election outcome. As well as selling Labour’s national “transformative, exciting vision” on the doorstep, he will also be wooing voters on local issues such as Johnson’s “betrayal” of residents on Heathrow’s third runway, and the future of Hillingdon hospital, parts of which are so dangerous and decrepit that child patients had to be moved out of its paediatrics department because it was deemed unsafe.

Volunteer activists from the leftwing grassroots group Momentum intend to flood the constituency in Milani’s support as part of its “Let’s Go” network. Momentum’s national coordinator, Laura Parker, said the strategy in Uxbridge would be focused on mobilising the seat’s large student base at Brunel.

Facebook Twitter Pinterest Boris Johnson at Brunel University on election day in 2015. Photograph: Matt Cardy/Getty Images

“Momentum will be running campus tours and working closely with youth groups to register students to vote and get them out on polling day,” she said. “It’s no wonder Boris Johnson has tried to gerrymander against this by changing the election date to the end of university term.”

Milani would also attract votes from residents “furious” over the Heathrow expansion, she said. “Boris Johnson has sold out students to a life of debt and precarity, sold out Heathrow families to airport bosses, and next wants to sell us all out for a disaster deal with Trump.”

Milani will hope to appeal to minority ethnic voters, whose numbers in the constituency have steadily increased, nearing 30% of the local population. His political opponents will undoubtedly point to some antisemitic remarks he has been accused of making as a teenager on Twitter, for which he has repeatedly apologised.

The Conservatives reportedly recently spend £1,178 in a single day on Facebook advertising aimed at 200,000 voters, calling for Uxbridge’s threatened police station to be kept open. Crime resonates with local people. Gurmail Singh, a Johnson constituent and president of the Gurdwara Sri Guru Singh Sabha in neighbouring Southall, said complaints about crime had gone up significantly in recent months. “Law and order, policing, hospitals – people will vote on these wider issues,” he said.

Facebook Twitter Pinterest Gurmail Singh, president of the Gurdwara Sri Guru Singh Sabha Sikh Temple in Southall. Photograph: Susannah Ireland/Guardian

Christine Harris, an art teacher, said having the police station in Uxbridge was vital for peace of mind. But Brexit, rather than local issues, would loom large for many voters, she said, “because people want it out of the way”.

Outside Uxbridge underground station, Dick Rodgers, from the Common Good party, was calling for pro-EU votes. “He’s got a decent majority but not insurmountable,” he said of Johnson.

Vote splintering over Brexit could play any way. There are rumours Richard Tice, the multimillionaire businessman and chairman of the Brexit party, could stand for parliament, but he has refused to confirm it would be against the prime minister, a decision that could hand the seat to Labour.

Equally a Liberal Democrat and Labour split could ensure a Johnson victory, though Milani believes this is an unlikely scenario given the Liberal Democrats lost their deposit in 2017.

While he cannot afford to outgun Johnson on social media, Milani has pledged to expend more shoe leather on the constituency’s streets, and can draw on an army of foot soldiers eager to be part of this David and Goliath battle. “Just think of the earthquake it would send to Westminster if we were to win, and the message it would send to the country. It is something I am willing to fight every day for,” he said.