Boris talks housing with jogger Esme Kilsby at a fishmongers off Hampstead High Street

“I only came here to get some sea bass – I wasn’t expecting Boris!” says jogger Esme Kilsby on finding the sandy-haired Mayor of London in her local fishmonger.

Boris Johnson has just made his way – after briefly marching off in the wrong direction down a side street – to the Coffee Cup in Hampstead High Street with Simon Marcus.

After a cuppa with Simon, who he credits as the “salvation” of the recently reprieved No 13 bus service, Boris stalks down the High Street handing out flyers to passers-by and busily praising Simon – a former amateur boxer – for his record of “punching peoples’ lights out” about the local issues that matter.

As we enter the final days in the race for the country’s tightest marginal seat, it’s clear from Boris’s spirited efforts to highlight the risks of Labour’s mansion tax policy – and Simon’s emphasis on the numbers telling him they’re switching to vote Tory – that the Conservatives are throwing the kitchen sink at Hampstead and Kilburn.

“The thing about the Conservatives and kitchen sinks is that we won’t deny the number of kitchen sinks or kitchens we have, unlike Labour”

Boris Johnson, Mayor of London

“The thing about the Conservatives and kitchen sinks is that we won’t deny the number of kitchen sinks or kitchens we have, unlike Labour,” says Boris.

Before Boris can galumph any further down the High Street, press pack in tow, he is collared by Peter McNeal, 81, who challenges him on the coalition government’s handling of the NHS.

“As far as Hampstead is concerned Boris, I’ve been waiting five weeks for a GP, I go to the Royal Free and the big issue in this election is the health service and it’s been neglected here.”

Boris looks ruffled and blusters his way through an answer on Labour’s waiting-time “disaster”, but is cheered by a passing car with two workers shouting “We love you Boris!”.

Boris Johnson and Simon Marcus pose with street-narrowing bollards on Church Row

Anna Strillacci, 36, walking her toddler in a pram, stops to chat with the pair about their manifesto promises.

Asked about her intentions for May 7, she says: “Me and my partner are bankers so with the Labour party’s mansion tax affecting houses like ours, for us it’s a no-brainer.”

En route through the historic Church Row, Boris halts and points at a row of handsome Grade II-listed houses: “Look! Isn’t that the famous scene in Ford Madox Brown’s painting? And aren’t those the famous Simon Marcus bollards?”

Gesturing towards a row of “handsome” stubby iron bollards, the mayor lauds Simon’s two-year campaign to install the road-narrowing bollards after neighbours complained of construction traffic threatening the structural integrity of their homes.

As Simon and the mayor gamely pose for pictures in front of the bollards, a passing jogger punches the air and shouts “Buller! Buller! Buller!” referencing the mayor’s membership of The Bullingdon Club, a notorious Oxford University drinking society.

Not one to miss a joke, Boris quips: “I’m sure that was bollard! bollard! bollard!”

But back to Esme in Hampstead Sea Food, who tells Boris and the Conservative hopeful that her vote will be won not by personalities but with policies.

“I am a ‘middle person’, a private renter and I work hard. Labour says they’re going to tax the rich but what about the middle person? I want to get on the housing ladder but I can’t afford my deposit,” she says.

Both recognise people on squeezed moderate incomes are “being hammered” and set out their pledge for building thousands more homes and rebalancing the London property market.

On his way out of the fishmonger’s, the mayor helps Simon in his play for Esme’s vote: “Good that she’s been buying sea bass, not salmon, sturgeon or kippers…”