MPs will see a full economic impact analysis before they vote on the final Brexit deal, Theresa May pledged on Wednesday, as the prime minister attempted to defuse a growing row over the leak of a secret report.

May’s promise was delivered as the government came under increased pressure over the highly confidential economic analysis that projected the UK would be worse off under three possible post-Brexit scenarios: a comprehensive free trade deal, single market access, and no deal at all.

Speaking to reporters on board her RAF Voyager flight to China, the prime minister said: “When the time comes for parliament to vote on the final deal, we will ensure that parliament has the appropriate analysis on which to be fully informed, on which to base their judgment.

“But it would be wrong to publish analysis before that analysis has been completed, and it would also be wrong to publish analysis which might prejudice our negotiating position.”

But justice minister Phillip Lee broke ranks to say the document raised questions about the government’s strategy. “The next phase of Brexit has to be all about the evidence,” he said in a series of tweets.

“We can’t just dismiss this and move on. If there is evidence to the contrary we need to see and consider that too. But if these figures turn out to be anywhere near right, there would be a serious question over whether a government could legitimately lead a country along a path that the evidence and rational consideration indicate would be damaging.”

Quick Guide What are Brexit options now? Four scenarios Show Staying in the single market and customs union The UK could sign up to all the EU’s rules and regulations, staying in the single market – which provides free movement of goods, services and people – and the customs union, in which EU members agree tariffs on external states. Freedom of movement would continue and the UK would keep paying into the Brussels pot. We would continue to have unfettered access to EU trade, but the pledge to “take back control” of laws, borders and money would not have been fulfilled. This is an unlikely outcome and one that may be possible only by reversing the Brexit decision, after a second referendum or election. The Norway model Britain could follow Norway, which is in the single market, is subject to freedom of movement rules and pays a fee to Brussels – but is outside the customs union. That combination would tie Britain to EU regulations but allow it to sign trade deals of its own. A “Norway-minus” deal is more likely. That would see the UK leave the single market and customs union and end free movement of people. But Britain would align its rules and regulations with Brussels, hoping this would allow a greater degree of market access. The UK would still be subject to EU rules. The Canada deal A comprehensive trade deal like the one handed to Canada would help British traders, as it would lower or eliminate tariffs. But there would be little on offer for the UK services industry. It is a bad outcome for financial services. Such a deal would leave Britain free to diverge from EU rules and regulations but that in turn would lead to border checks and the rise of other “non-tariff barriers” to trade. It would leave Britain free to forge new trade deals with other nations. Many in Brussels see this as a likely outcome, based on Theresa May’s direction so far. No deal Britain leaves with no trade deal, meaning that all trade is governed by World Trade Organization rules. Tariffs would be high, queues at the border long and the Irish border issue severe. In the short term, British aircraft might be unable to fly to some European destinations. The UK would quickly need to establish bilateral agreements to deal with the consequences, but the country would be free to take whatever future direction it wishes. It may need to deregulate to attract international business – a very different future and a lot of disruption.

The leaked document, obtained by Buzzfeed and intended to be shared only with cabinet ministers, said that over a 15-year period national income would be 8% lower under a no-deal scenario, around 5% lower with a free trade agreement with the EU, and about 2% lower with a soft Brexit option of single market membership.

May’s intervention comes amid an angry backlash after her Brexit minister Steve Baker claimed government officials had never produced a correct economic forecast – comments branded unacceptable by Bob Kerslake, the former head of the civil service.

Overnight, May appeared to back her minister’s comments. “First of all, as I think Steve Baker made clear in the House of Commons today, it would be wrong to describe this as ‘the Brexit impact assessment’.



“What has been seen so far is a selective interpretation of a very preliminary analysis, which ministers have not signed off, have not approved, and which doesn’t actually even look at the sort of deal that we want to deliver in terms of the future relationship with the European Union.”

Downing Street insisted the document did not cover May’s preferred outcome – a bespoke trade deal – though European leaders have repeatedly said there is little room for movement beyond a Canada-style deal, which the document predicts would still damage the economy.

Kerslake said the attack was part of a “wider narrative from Brexiters” to paint senior officials such as Olly Robbins and Sir Jeremy Heywood, reported to have been responsible for the document and its planned circulation to senior ministers, as secret remainers.

Baker, a former leading figure in the Leave campaign, told MPs, after being summoned to explain the leaked analysis, that such documents were “always wrong”.



Labour will attempt to force the government to publish the full version of the study by using a “humble address”, the same little-used procedure that forced David Davis to release information about the potential impact of Brexit on different sectors of the economy. Keir Starmer, the shadow Brexit secretary, said: “Ministers cannot keep sidelining parliament to hide the deep divisions within their own party.”



The party could win a vote on the issue on Wednesday after 47 MPs – including Conservatives Ken Clarke, Anna Soubry and Antoinette Sandbach – signed a letter demanding the “secret study” be released.