Boris Johnson has vowed to put a stop to any rise in so-called “sin taxes”, which include levies on alcohol, tobacco and unhealthy foods.

The Tory leadership frontrunner said that as prime minister he would launch a review into whether the taxes work and how they impact low earners.

He promised to freeze all sin taxes at their current levels and not introduce any new ones until the review has concluded.

The former foreign secretary said leaving the EU would create a “historic opportunity” to evaluate taxes in the UK.

Last week Mr Johnson spoke out against proposals to extend the current “sugar tax” to include milkshakes.

The levy on sugary drinks was introduced last April, and was widely praised by doctors and health experts.

Professor Dame Sally Davies, the chief medical officer for England, is currently looking into whether it should be extended to other unhealthy food and drink products.

The review was commissioned by Matt Hancock, the health secretary and a prominent supporter of Mr Johnson.

Announcing his plan to freeze sin taxes Mr Johnson said: “The recent proposal for a tax on milkshakes seems to me to clobber those who can least afford it.

“If we want people to lose weight and live healthier lifestyles, we should encourage people to walk, cycle and generally do more exercise.”

He added: “Rather than just taxing people more, we should look at how effective the so-called sin taxes really are, and if they actually change behaviour.

“Once we leave the EU on 31 October, we will have a historic opportunity to change the way politics is done in this country.

“A good way to start would be basing tax policy on clear evidence.”

Biggest lies told by Boris Johnson Show all 5 1 /5 Biggest lies told by Boris Johnson Biggest lies told by Boris Johnson Made-up quote for The Times Johnson was sacked from The Times newspaper in the late 1980s after he fabricated a quote from his godfather, the historian Colin Lucas, for a front-page article about the discovery of Edward II’s Rose Palace. “The trouble was that somewhere in my copy I managed to attribute to Colin the view that Edward II and Piers Gaveston would have been cavorting together in the Rose Palace,” he claimed. Alas, Gaveston was executed 13 years before the palace was built. “It was very nasty,” Mr Johnson added, before attempting to downplay it as nothing more than a schoolboy blunder. PA Biggest lies told by Boris Johnson Sacked from cabinet over cheating lie Michael Howard gave Boris Johnson two new jobs after becoming leader of the Conservatives in 2003 – party vice-chairman and shadow arts minister. He was sacked from both positions in November 2004 after assuring Mr Howard that tabloid reports of his affair with Spectator columnist Petronella Wyatt were false and an “inverted pyramid of piffle”. When the story was found to be true, he refused to resign. PA Biggest lies told by Boris Johnson Broken promise to boss In 1999 Johnson was offered editorship of The Spectator by owner Conrad Black on the condition that he would not stand as an MP while in the post. In 2001 he stood - and was elected - MP for Henley, though Black did allow him to continue as editor despite calling "ineffably duplicitous" PA Biggest lies told by Boris Johnson Misrepresenting the people of Liverpool As editor of The Spectator, he was forced to apologise for an article in the magazine which blamed drunken Liverpool fans for the 1989 Hillsborough disaster and suggested that the people of the city were wallowing in their victim status. “Anyone, journalist or politician, should say sorry to the people of Liverpool – as I do – for misrepresenting what happened at Hillsborough,” he said. PA Biggest lies told by Boris Johnson ‘I didn’t say anything about Turkey’ Johnson claimed in January, that he did not mention Turkey during the EU referendum campaign. In fact, he co-signed a letter stating that “the only way to avoid having common borders with Turkey is to vote Leave and take back control”. The Vote Leave campaign also produced a poster reading: “Turkey (population 76 million) is joining the EU”

But Deborah Arnott, chief executive of Action on Smoking and Health, said reducing taxes on tobacco would be a ”grave error”.

She said: “Smoking kills more than 100,000 people in Britain each year. And the evidence from other countries is clear, when taxes stop going up, smoking rates are likely to stop going down.

“Making tobacco less affordable via taxation is considered to be the most effective means of discouraging young people from starting to smoke and helping adult smokers to quit.