Andy Burnham, the Labour mayor of Greater Manchester, has won a new convert. Gemma Fish, 38, who runs a charity in Salford, has never voted before but in elections on Thursday she expects to change the habit of a lifetime. “He stood up for Manchester,” she said.

Burnham last October memorably resisted Boris Johnson’s plan to lock down the city without what he regarded as adequate financial help. “It’s brutal to be honest, isn’t it?” Burnham said in an emotional press conference outside the city’s Bridgewater Hall.

The mayor was dubbed the “king of the north” — exactly the kind of local champion envisaged when George Osborne, former Conservative chancellor, created a new breed of metro mayors first elected in 2017.

But the arrival of powerful figures who have broken the grip of Westminster over the country’s political life has created tensions. Nicola Sturgeon, Scotland’s pro-independence first minister, is the beneficiary of Tony Blair’s big push on devolution in the late 1990s.

Sadiq Khan, Labour mayor of London, holds another post created by Blair and is known to get under Johnson’s skin. Meanwhile, Andy Street, Tory mayor of the West Midlands, Ben Houchen, the high-profile Tory mayor of Tees Valley, and Burnham are beneficiaries of more recent Tory-led devolution.

Osborne last year said Johnson should “double down on devolution” and give mayors new powers; he said they were “a fantastic success story” and that every area should have one.

But under Johnson, himself mayor of London from 2008-16, the devolution agenda has stalled. Lord Michael Heseltine, former Tory deputy prime minister and champion of decentralisation, said Westminster had grown jealous of the popularity of the new breed of metro mayors.

“The agenda is dead,” he said. “Departments don’t want to lose power, local MPs don’t want to see mayors taking some power, the Treasury is suspicious of anything that creates more pots of money.”

Heseltine said Burnham’s stand-off with Johnson last year “probably didn’t help”. He fears Johnson is reverting to the old ways of handing out government cash directly from Whitehall to local authorities — sidelining regional or national figures such as Burnham and Sturgeon.

A 2019 Conservative manifesto pledge to set out the next stage of devolution in a white paper in 2020 was broken — the Covid-19 crisis was blamed for the delay — and the exercise has now been wrapped up into a wider “levelling up” white paper promised for later in 2021.

The Tory manifesto called for “full devolution across England” and Conservative party officials say Johnson is still wedded to this agenda. But they add the big proviso that the creation of new elected mayors in the regions had to be done with enthusiastic local support.

Eight city regions in England have metro mayors: Greater Manchester, Liverpool, the West Midlands, Tees Valley, the West of England, Cambridgeshire and Peterborough, Sheffield and North of Tyne. West Yorkshire will become the ninth on Thursday. Seven of them will elect mayors this week.

Johnson’s lack of engagement on devolution appeared to be confirmed on a campaign visit to Gloucestershire last month when he was unable to name the Tory West of England mayor, Tim Bowles. However, the success of Conservative mayors such as Houchen and Street has shown that the party can use mayoralties as a bridgehead in former Labour areas.

Street continues to lobby for fresh powers for mayors, including the ability to retain some taxes locally, for example stamp duty or VAT. “That’s true devolution,” he said.

Metro mayors have different powers and budgets. All control local transport, skills and economic development and have extensive planning powers. Greater Manchester has the most comprehensive deal, including joint control with government of health and social care.

Polling for Centre for Cities, a think-tank, by Savanta ComRes in April found that 83 per cent of people supported greater devolution.

Burnham has shown the political potential of the city mayor’s role. While Labour leader Keir Starmer is braced for a tough night at the polls in a series of local elections across Britain on Thursday, the Manchester mayor is expected to be comfortably re-elected.

Indeed most of the incumbent mayors — Labour and Tory — expect to be returned to office, having spent the past few years speaking up for their area and standing up to the politicians at Westminster.

Burnham, out campaigning in sleet and hail in Salford on Tuesday, is the bookies’ favourite to succeed Starmer as party leader, even though he is not an MP. “I’m happy here — I feel more at home here,” the former Labour cabinet minister said when asked about a return to Westminster. But he added: “I’m not going to rule it out completely.”

Burnham said mayors must play a key part in Johnson’s economic agenda and insisted he wanted to work with the prime minister.

“If the government is going to level up, you can’t do it from an office in Whitehall,” he said. “Where they treat us with respect and fairly, we will work with the government. Any other form of devolution won’t work.”

Burnham claimed there was “punishment talk” from the government after he resisted the Covid-19 lockdown last October, but said: “It’s fake devolution if the government makes you go on bended knee and do what they want.”

Elaine Wrigley, who with her husband Mark owns the Atlas Bar in Manchester, said Burnham was one of the few politicians to stick up for hospitality businesses when they were closed in October by the government.

“He fought for the people of Greater Manchester when the government was not listening,” she added.

Lord Jim O’Neill, former chief economist at Goldman Sachs and an architect of Osborne’s metro mayor plan, said that may be part of the problem. “They don’t like mayors who are not Tory — it’s plain and simple.”