AFTER Labour increased its majority in the Peterborough by-election, Jeremy Corbyn has told the Tories and the media: “Underestimate us at your peril.”

At a victory rally in Peterborough today, the Labour leader congratulated Lisa Forbes on becoming Labour’s newest MP.

“We offer the politics of hope, to end austerity, to fund our schools properly, to employ our police properly, to give our young people a future in this country,” he said.

Mr Corbyn took a shot at the right-wing media, which had predicted a Brexit Party victory, saying: “All the experts who wrote Labour off yesterday – underestimate Labour at your peril.

“We are strong, we are very determined to offer decent services, decent housing, decent healthcare and jobs for the future.”

On the day that Prime Minister Theresa May stepped down as Tory leader, he also challenged all potential candidates to replace her to call a general election.

“My message is to all the squabbling contenders for the Tory Party leadership: bring it on.

“We are ready for a general election at any time – that election will deliver a government for the many, not the few.

“Instead of a country for a very rich few, we will be a country that cares for all.

“Our party will take us to that so much better place.”

Despite the Brexit Party’s Mike Greene being the bookie’s favourite to win, Ms Forbes, a Unite union organiser from the left of the party, gained 10,484 votes to Mr Greene’s 9,801.

Labour’s majority in Peterborough is now up from 607 votes in the 2017 general election to 683.

This is despite the Brexit Party spending over £15,000 on targeted Facebook advertisements to Peterborough residents during the campaign.

Both Labour’s supporters and detractors have credited the party’s strategy of mobilising hundreds of activists and focusing on bread-and-butter issues for the victory.

Mr Corbyn praised the “people-powered campaign” organised by party chair Ian Lavery, shadow minister Louise Haigh and campaigning group Momentum.

Anti-Brexit candidates fared poorly, with the Change UK-endorsed candidate Pete Ward receiving 45 votes and the UK-EU Party’s Pierre Kirk gaining 25.

Both were beaten by Alan “Howling Laud” Hope of the Monster Raving Party, who came 10th with 112 votes.

A Labour doorknocker who did not wish to be named told the Star: “My favourite moment of the campaign was Peter Ward pulling up in his Tesla [electric car] and saying: ‘Don’t you know who I am?’.

“I hadn’t even the slightest clue and I still don’t really know now.”

Party chair Ian Lavery applauded the “hard work, dedication and commitment” of Labour supporters and members knocking on doors in the constituency.

He said: “The real issues facing Peterborough were the increase in crime, the lack of police officers, poor education results, among many other things – poor living standards, poverty.”

Former TGI Friday’s striker and Labour councillor Lauren Townsend heaped praise on Ms Forbes, saying: “I am over the moon that Lisa has been elected.

“A solid trade unionist, who I’ve had the pleasure of attending Unite courses alongside, Lisa Forbes will be a strong advocate for the people in her constituency and always champion those who need a little extra support or empowerment to affect change in their communities.”

CWU general secretary Dave Ward pointed out that in the run-up to the by-election, Mr Corbyn was “being urged to forcefully commit to making Labour a party of Remain no matter what.

“I can tell you now that nothing would have been won in Peterborough if that had happened.

“If we had taken their advice, we would have lost a Labour MP in Peterborough and been forced to roll out the pomp and ceremony of Parliament to some far-right Brexit Party fraud.”

Change UK did not respond to request for comment on its result.