Labour has promised to level the playing field for small businesses with an overhaul of the business rates system.

Speaking at a brewery in his constituency of Holborn and St Pancras, Sir Keir Starmer criticised the Conservative Government for failing to “fix” the system which he said has caused problems for businesses for a “long time”.

The party is also pledging to accelerate the establishment of banking hubs, stamp out late payments of invoices by forcing large firms to report on their payment practices, and crack down on antisocial behaviour to “revitalise” high streets.

Speaking at 3 Locks Brewing Company in Camden, the Labour leader said a “better system” was coming, adding: “We want to replace them with a system that works better, because at the moment there’s not a level playing field between businesses that are online and those that are sort of bricks and mortar.

“It’s been a problem for a long time, the Government hasn’t fixed it and small businesses have all gone through a really hard time in recent years.

“So that’s our plan, we want small businesses to thrive because they are the backbone of our economy and they need that stability in our economy, and they need to know that their energy bills are actually going to be lower and stable.”

Labour first put forward its plan to “breathe new life” into Britain’s high streets in April, drawing approval from trade bodies for its proposed overhaul of the business rates system.

But it is not clear what Labour would replace business rates with, leading some to call for more clarity.

After pulling the first pint of the day at 10.55am, Sir Keir said that “if all else fails”, he will be back at the north London brewery on July 5.

He was joined by Dragons’ Den star Deborah Meaden, who described the party’s Great British Energy plans as “absolutely brilliant”.

She told the PA news agency: “I think GB Energy is absolutely brilliant, I think it does everything that I care about.

“Businesses don’t like being out of control of costs and energy is one of those costs that simply fluctuates beyond your control.”

Sir Keir said his party’s Great British Energy plan is “very popular” with small businesses.

“They’ve had a really hard time with this Government in recent years, so our plan is to support small businesses and give them that chance that they need,” he said.

“That does involve replacing rates, because business rates put a real drag on businesses. It also involves stabilising the economy, of course, and Great British Energy, because what’s come up here comes up with all small businesses – energy is too expensive.

“What you can’t have if you run a small business is sort of costs that you can’t control, so Great British Energy, a publicly owned company for renewables, is very, very popular with small businesses.”

Asked if he would be cutting taxes, Sir Keir said there “won’t be any surprises on tax” in Labour’s manifesto.

He added: “All of our plans are fully costed, fully funded, none of them involving tax rises over and above those that we have already set out.”

Rachel Reeves, who was also touting Labour’s offer for growing businesses on the Farnborough high street with retail guru Mary Portas on Saturday, said “nothing in our plans requires any new taxes”.

Writing in The Sun, the shadow chancellor said: “I want taxes to be lower. But unlike the Conservatives I am not going to promise you a tax cut without telling you where the money is going to come from or without being able to guarantee you it will be delivered.

“And the approach the Conservatives are taking now is the same as the approach Jeremy Corbyn took – and I totally reject it.

“I’m not going to offer you a fantasy manifesto that writes cheques we could never cash. I will never do this.”

At the canal-side craft brewery, Sir Keir met young people who are voting for the first time this year.

The students said scrapping the Rwanda migrants scheme, helping young adults through the cost-of-living crisis and improving the education system should be priorities for the next government.

One of the students, Dan Bilenga, said he had met Sir Keir previously when he bumped into him on the streets of Camden and asked him for a work experience opportunity.

The 18-year-old told PA: “I told him my situation said I was looking for some work experience, and then I wasn’t expecting anything but he got back to me.”

Mr Bilenga, who attends Leeds University where Sir Keir studied, added: “He’s a real guy, he sticks to his word, he said he would do something and he did it.”