Boroughs considered safe by the Conservatives will be up for grabs in the May contest © Anthony Devlin/PA

Britain’s Conservatives are heading for their worst local election performance in London since the 1960s and face the loss of three flagship boroughs, according to research by YouGov.

The survey for Queen Mary University of London appears to confirm the trend in which Labour increases its support in large conurbations while the Tories remain strong in rural areas and smaller towns. It found that 28 per cent of Londoners supported the Tories against 54 per cent for Labour.

The totemic Conservative boroughs viewed as vulnerable in the May 3 contest are Barnet, Wandsworth and Westminster.

The local elections come at a testing time for Theresa May, who is going into critical Brexit negotiations under fire from pro- and anti-EU MPs in her own party.

A series of setbacks in May could weaken the prime minister further, her allies fear, galvanising MPs who want a change of leadership.

One Tory official predicted a “bloodbath” in the vote and warned that wards that used to be considered a “safe win” were “likely” to be lost to Labour.

“I don’t think the party has come up with anything positive to offer London so I reckon it will be a bit of a bloodbath in May,” the official said. “From what I can gather we’re not going to do well across pretty much all of London.”

Andrew Rosindell, a Tory MP whose seat is in the capital, admitted: “In London there is problem with Remain voters still wanting to punish the Conservatives. But not so in the borough of Havering [outer east London], where Leave voters are punishing Labour for being Remain and Ukip voters are swinging Tory.”

A fellow Tory MP said: “If it goes as badly as I think it’s likely to go we will be absolutely trashed, especially in London.”

The YouGov research suggests a significant shift towards Labour in the capital since the 2014 local polls, with a swing of 13.4 per cent in the inner boroughs and 4.2 per cent in the outer suburbs.

The loss of Wandsworth, Margaret Thatcher’s favourite council that prided itself on low council taxes a generation ago, would be a blow for the Tories.

Barnet in north London is also symbolic because it has been hailed as a model for efficiency savings and outsourcing during years of austerity cuts, earning itself the nickname “EasyCouncil”. The Tories have a majority of one seat on its council.

Westminster is another longstanding Conservative council, with large numbers of affluent residents.

There is also a chance of Hillingdon in outer west London changing hands if Labour improves its position between now and May, according to the research.

Philip Cowley, a professor at the university’s Mile End Institute, said Labour appeared on track for the highest vote share in London of any party since 1968.

“The massive swing in inner London in this poll is enough to turn both Westminster and Wandsworth red. In outer London, they should take Barnet. Hillingdon looks very close, and although boundary changes make Bexley very difficult to predict, that, too, looks as if it could be close,” he said.

One Labour MP said the opposition party was also hoping to do well in the West Midlands and in Greater Manchester.

The Queen Mary research found 58 per cent of Londoners felt Sadiq Khan, the Labour mayor, was doing well but 23 per cent thought he was doing badly.

It also suggested that the Tories are behind Labour among black and minority ethnic voters by 78 per cent to 12 per cent. Among 18-24 year olds the split was 8:1 in favour of Jeremy Corbyn’s party. The only age group with majority support for the Tories was the over-65s, the study found.

“On paper, these swings mean Kensington and Chelsea should remain safe for the Conservatives, but the post-Grenfell situation here means I would advise caution. Basically, this poll means that the Conservatives are facing difficulties in almost every London council they still control,” said Prof Cowley.

But Nickie Aiken, leader of Westminster council, was sceptical of the results: “We are not going to lose Westminster. I’m certainly not complacent but our track record speaks for itself. The response we are getting across Westminster on the doorsteps is that they trust us.”

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