George Osborne has taken a swipe at Boris Johnson as he laid out a doomsday scenario if the UK-voted to leave the EU - warning income tax could go up 8p under "Brexit".
The Chancellor today presented the Treasury's analysis of the impact of voting to leave at the June 23 in-out referendum. The centre-piece claim, briefed overnight, is families would be £4,300 worse off.
The 200-page report, published today, goes on to say adopting a Canada-style trade agreement on leaving the EU would shrink the UK economy by 6.2% within 15 years - leaving a £36bn "black hole", or the equivalent to 8p on the basic rate of income tax.
Outlining the case at a speech in Bristol, Osborne had a jab at the London mayor and his potential Tory leadership rival, who is opposing the Government line by campaigning to quit the EU.
Johnson famously said his policy on cake was “pro having it and pro eating it”.
In his speech, and in an early morning interview with Radio 4's Today programme, Osborne made a deliberate reference to the line.
“What is not honest and what is economically illiterate is to say we can have all the economic benefits of being in the EU and at the same time leave. That is having your cake and eating it.”
The Treasury document sets out the three main alternative models for Britain on leaving the EU, namely the "Norway model", the "WTO model" and the "Canada model".
Under each scenario, the UK is significantly worse off.
The worst arrangement for the UK is the "WTO model", where Britain remains in the World Trade Organisation but without a specific agreement with the EU.
As the far right column indicates, GDP, the measure of economic activity, would be 7.5% lower by 2030, equivalent to a £45bn slump in tax receipts.
The other significant table relates to what the £45bn - or £36bn under the "Norway model" and £20bn under the "Canada model" - is the equivalent to.
The table suggests income tax would have to be hiked between 4p in the pound and 10p, and could represent more a hit bigger than the schools budget in England or half the money spent on the NHS.
But Stewart Jackson, Conservative MP and "out" campaigner, questioned the validity of the analysis.
Treasury analysts used a variety of sources for their analysis, including a text based on the impact of 1956 Suez Canal crisis.
Brexit-ers are also likely to point to just a passing reference to immigration - which will be debated fiercely - though the one passage that does essay the impact on the population suggests there could be an extra 3 million people in UK by 2030.
The Vote Leave campaign group dismissed the analysis.
Tory MP John Redwood said: "The Prime Minister was one of the senior advisers working in the Treasury while John Major's Government tried to keep this country in the EU's disastrous Exchange Rate Mechanism.
"The ERM destroyed jobs and caused misery for families across the country.
"The Remainers were wrong then, and they are wrong now - people should not trust their judgement on the EU."