Labour has launched a new attack ad against Rishi Sunak – and it has ended up on the Tory-supporting Conservative Home website.

In the ad, which was launched as Labour visited the Conservative-held seat of Wellingborough ahead of the upcoming by-election there, the party claims the government had left working people with a “raw deal” because of hidden tax rises.

It claims that the benefit felt by cuts to national insurance, which will take effect from tomorrow, will be effectively cancelled out by the fact that frozen income tax and national insurance thresholds have drawn people into higher tax bands.

The poster was unveiled on a shopfront and ad van as Labour’s shadow chancellor Rachel Reeves joined shadow paymaster general Jonathan Ashworth in Wellingborough, where the former MP Peter Bone was ousted for breaching the MPs’ code of conduct.

The ad will also be published online and in regional newspapers across the country.

By Friday afternoon, the ad, which is presented in the style of a mock shopping deal advert, had already appeared on the Conservative Home website, which supports Mr Sunak’s party and is influential with grassroots Tory activists.

Politics latest: Could the election be in November?

Chancellor Jeremy Hunt announced in the autumn statement that national insurance would be cut by two percentage points from 12% to 10% from 6 January – saving those on an average salary of £35,000 over £450 a year.

Mr Hunt also abolished NI payments for the self-employed, known as class two national insurance, to recognise the government “values their work”.

But Ms Reeves said that despite the changes in the autumn statement, “for every 10p that they have increased taxes on working people, they are only giving 2p back” – something she called a “drop in the ocean”.

She claimed the average family was paying £1,200 extra tax this year “because of choices by Rishi Sunak and this Conservative government”, adding: “Never have people paid so much in tax and got so little in return in the form of public services.”

The government’s policy is to keep income tax and national insurance thresholds frozen until 2028, meaning millions of workers will be pushed into higher tax bands because of inflation.

Labour leader Sir Keir Starmer has so far refused to commit to unfreezing tax thresholds if his party wins the next general election – saying he won’t make promises he can’t keep – but that he does want to “lower the burden of working people”.

The Liberal Democrats have also highlighted the impact of frozen tax thresholds on the public, with its research suggesting that the combined impact of taxes, mortgage rises and food inflation could cost the average household more than £4,700.

Labour’s new attack comes as the main parties gear up for what is predicted to be a long and fractious campaign for the general election, which the prime minister has hinted will take place in the autumn of this year.

Speaking to broadcasters on a visit to a youth centre in Nottinghamshire on Thursday, Mr Sunak said his “working assumption” was that the country would have a general election “in the second half of this year”, adding: “And in the meantime I’ve got lots that I want to get on with.”

Read more:
A delay in calling the election is the last thing Starmer needs
What 2024 could have in store for UK politics

Responding to Mr Sunak’s remarks which hinted at an autumn vote, Sir Keir accused the prime minister of “delaying” the inevitable and asked: “What is he hiding from the public?”

He told Sky’s political editor Beth Rigby that he would “like to see an election as soon as possible”, adding: “People can’t afford for the prime minister to be squatting for months on end this year.”

Deputy Conservative Party chairman Brendan Clarke-Smith said: “The Labour Party have admitted they won’t cut taxes – instead their £28bn unfunded spending will result in thousands of pounds of tax rises for the British people.

“Tomorrow we will deliver the biggest tax cut to National Insurance in modern history for 27 million workers, before we go further and cut taxes for the self-employed because of the long-term decisions we have taken to have inflation and strengthen the economy.”