Five years ago, London was a Conservative city. But the party has written off its chances of winning there this week or in the foreseeable future. How have the Tories lost touch with a place that in living memory voted for both Boris Johnson and Margaret Thatcher?

That’s the question I’m trying to answer in my forthcoming book The Lost City: How London Fell Out Of Love With The Tories (9 Sept., Pundit Press). I’ve spent more than a year living among the “Cockneys”, as Londoners are known, and coming to understand their ways, from their love of flat white coffees and IPA beer to their tiny, expensive housing.

James Trevelyan sips his cappuccino as he sits outside a coffee shop in Dulwich, a southern district of London, with his friend – or “mate” – Sebastian Holt. The pair, both now in their eighties, have known each other since 1970 – “no, 1969!” – when they both worked as script editors in the BBC’s Light Entertainment Department.

“Oh, you should have seen Television Centre in those days!” James leans back, his eyes nearly closed as he reminisces. “Always buzzing. The people! Cleese, Morecambe, Odie! Real craftsmen, carving out gags one by one. It was hard work, but there was such pride in being a part of it.” He takes another sip. “We used to make things in this town. We used to make television. I worked on 67 episodes of The Goodies. Sixty-seven! Can you imagine that today?” They sit in silence for a moment, honouring happier days.

Sebastian’s son has followed in his father’s footsteps, he says, “but it’s a different world now. There’s no security. It’s all freelances, trying to sell jokes at thirty quid a time. It’s no life.”

It’s easy to dismiss these two old men as a pair of pensioners hankering for a lost past. But perhaps their nostalgia for a more straightforward era helps to explain the deep resentment felt by so many in this city.

London traces its history back to Roman times. William the Conqueror built a castle there that still stands, the famous London Tower, where for centuries threats to the crown were imprisoned, guarded by the red-coated Beefmasters. As the country grew, so did London. The fruits of empire were unloaded at its docks. And when war came, it came to this city. It wasn’t just Glasgow and Liverpool that were bombed in the Blitz: London got its share, too.

Hampstead is a pretty little well-to-do area on the north side of the city, evocative of Jesmond or Morningside. For voters there, the Brexit referendum of 2016 was a turning point.

“It was a chance to tell the government that we really liked things just the way they were,” Jocasta Webley, an insurance broker, explains as she sits on the “Heath”, as locals call the area’s park, eating a traditional local lunch, a Humous and Chipotle Wrap. “People get upset when you say it these days, but I liked being able to hire a graduate from Eastern Europe to look after my children. And I really felt David Cameron was interested in people like me. Boris Johnson only wants to talk about fishermen.”

London voted strongly against Brexit, and many say their votes have been ignored. “Bloody Conservatives only care about Redwall, wherever that is,” says Katie Garfield, a nurse who lives in East Ham. She is voting Labour this Thursday. Some find it surprising that Labour leader Keir Starmer, son of a toolmaker, graduate of Leeds University, should have such a wide appeal in this affluent, southern city. But Jocasta’s friend Thomas Reeve is a fan. “It feels like he’s one of us,” explains the corporate lawyer.

Many in London also struggle with Johnson’s character. “All those oh-so-sophisticated people in Hartlepool might not care if he’s running around fathering kids everywhere and trying to get his rich friends to buy him wallpaper,” says Faith Anstee, a social worker in Brixton, “But we have traditional values here. We know the difference between right and wrong, and we still think it matters.”

Demographic changes have created their share of tensions

Demographic changes have created their share of tensions. In Walthamstow, an area west of the city centre still scarred by the closure of its dog track, there is anger about the recent waves of incoming hipsters looking for somewhere they can afford to start a family. “I’m sure some of them are nice enough, but they eat funny food,” said Abdul Aziz, 68, who has lived in the area for four decades. “And some of them don’t wash.” The Asian supermarket where he used to shop has been turned into a microbrewery, the third to open in the area in the last year.

Parents fear losing touch with their children, who are increasingly likely to go to university in far-flung places such as Oxford, Durham or Exeter. Wendy and John Melling’s daughter Sam went to Nottingham University eight years ago, but hasn’t returned to live with them in Fulham. “She says Streatham is all she can afford,” Wendy says, downcast. “How is she going to bring up children in a place like that? What will their accents be?”

Again and again as I talk to people, I hear the same refrain. “Open the papers and it’s Teesside this and Stoke-on-Trent that,” said Brian Rankin, a currencies trader from Twickenham. “When is someone going to stand up for people round here, and traditional industries like investment banking or management consultancy? This lot won’t even let us use the woodburning stoves our parents did. What sort of life is it they want for us? We just want our country back.”