Sir Keir Starmer attacked Boris Johnson as a “trickster” with no plan for running the country as he insisted Labour could win the next election.

In his first in-conference speech as Labour leader, Sir Keir said he is “totally serious” about defeating an inadequate Government that “can’t keep the fuel flowing” or supermarket shelves stocked.

But after a bruising conference in Brighton which has seen him clash with the Labour left, Sir Keir was heckled by activists over his refusal to support a £15 hourly minimum wage.

In a highly personal speech, the Labour leader described “family and work” as “the two rocks of my life – the two sources of what I believe to be right and good”, highlighting his background as the son of a toolmaker and an NHS nurse who later needed long-term care.

He also contrasted his past as the head of the Crown Prosecution Service with the Prime Minister’s background as a newspaper columnist.

“It’s easy to comfort yourself that your opponents are bad people,” he said.

“But I don’t think Boris Johnson is a bad man. I think he is a trivial man. I think he’s a showman with nothing left to show. I think he’s a trickster who has performed his one trick.

“Once he had said the words: ‘Get Brexit Done’, his plan ran out. There is no plan.”

He claimed Britain had been left “isolated and irrelevant” on the world stage under Mr Johnson.

But he also recognised Labour’s failure under Jeremy Corbyn to defeat the Tories, and praised the party activists who had saved it from “obliteration” in the landslide defeat in 2019.

“I can see the ways in which we can remake this nation and that’s what we get to do when we win,” Sir Keir said.

“Yet, in a way, the more we expose the inadequacy of this Government the more it presses the question back on us.

“If they are so bad, what does it say about us? Because after all in 2019 we lost to them, and we lost badly. I know that hurts each and every one of you.

“So, let’s get totally serious about this – we can win the next general election.

“This Government can’t keep the fuel flowing, it can’t keep the shelves stocked, and you’ve seen what Boris Johnson does when he wants more money – he goes straight for the wallets of working people.

“Labour is the party that is on the side of working people.”

Setting out the contrast between himself and the Prime Minister, Sir Keir said: “The one thing about Boris Johnson that offends everything I stand for is his assumption that the rules don’t apply to him.”

He referred to the actions of former No 10 aide Dominic Cummings and then health secretary Matt Hancock during the lockdown.

He added: “When I got pinged, I isolated. When Boris Johnson got pinged, he tried to ignore it. That’s not how I do business.”

Referring to contracts “handed out to friends and donors” and the row over the funding of the Prime Minister’s Downing Street flat, Sir Keir said: “Politics has to be clean; wrongdoing has to be punished. There are times in this Parliament when I feel as if I have my old job back.

“On behalf of a public that cares about cleaning up politics, I put this Government on notice.”

Sir Keir also drew on his previous profession to position Labour as the party of law and order, promising to fast-track rape and sexual assault cases and tougher sentences for rapists, stalkers and domestic abusers.

“This is part of who we are because this is part of who I am,” he said.

The Labour leader said the coronavirus pandemic exposed the “failure of the Government’s duty of care over 11 years”, with the death toll “worse than it needed to be”.

“There are cracks in British society and Covid seeped into them,” he said.

On education, Sir Keir set out plans for “the most ambitious school improvement plan in a generation”.

In a message to the Government, he said: “If you can’t level up our children, you’re not serious about levelling up at all.”

Sir Keir also set out how Labour would tackle climate change, including a “national mission” to fit out homes to make them warm, well insulated and energy efficient over the next decade – creating thousands of jobs in the process.

Scotland is in the unfortunate position of having two bad governments - the Tories at Westminster and the SNP at Holyrood

There would be a new Clean Air Act and everything a Labour government does will have to meet a “net-zero” test to ensure that prosperity “does not come at the cost of the climate”.

While Sir Keir distanced himself from the Corbyn era – promising “we will never under my leadership go into an election with a manifesto that is not a serious plan for government” – he praised the record of the New Labour years.

Highlighting improvements in healthcare, social mobility and poverty reduction, he said: “You want levelling up? That’s levelling up.”

He accused the Prime Minister of adopting a “cavalier” approach to future of the United Kingdom which is “placing it in peril”.

Sir Keir said: “Scotland is in the unfortunate position of having two bad governments – the Tories at Westminster and the SNP at Holyrood.”

Former prime minister Gordon Brown will lead a Labour commission on the future of the union, Sir Keir said, adding: “We are greater as Britain than we would be apart.”

Sir Keir was interrupted a number of times by hecklers, with some in the conference centre holding up red cards in protest.

The Labour leader hit back and asked whether the detractors were “shouting slogans, or changing lives”.

Party activist Carole Vincent, from the Leyton and Wanstead constituency in east London, said afterwards that she expected to be thrown out of the party for heckling the leader – and added she did not expect Sir Keir to survive in post until the next conference either.

She told the PA news agency: “I don’t consider it to be heckling, I consider that I stood up and spoke out because it needed to be said.

“He had ignored – and this conference has ignored – people that have been standing up and asking for him to guarantee the 15% rise for the NHS, a £15 minimum wage.”

She said Sir Keir had 10 pledges during his leadership campaign but claimed he has “reneged on most of those”.

Sir Keir arrived on stage to the sound of Brighton resident Fatboy Slim’s Right Here, Right Now. As a child he had music classes at school with the future DJ.

At the end of the speech – which lasted almost 90 minutes and ran to more than 7,000 words – Sir Keir was joined by his wife Victoria.

He was given a lengthy standing ovation as he shook hands with activists before leaving the conference hall.