The Treasury has not carried out a detailed economic forecast of Britain's Brexit options since the referendum, Sky News has learnt.
In an interview with Sky News, the Chancellor Philip Hammond repeatedly refused to say whether he had produced another such assessment since the vote on 23 June.
Last month the Brexit Secretary, David Davis, admitted that his department had produced no such analysis.
Some had assumed that the Treasury would carry out its own work, given that the Government has since narrowed down the options and ruled out staying inside the EU's single market.
However, senior Government sources have now told me that in the wake of the vote, the Treasury was so disturbed by the response to its forecasts of an economic downturn that it decided to "lock them in the cabinet" and not carry out any detailed updates.
The news comes as the Chancellor and Prime Minister embark on foreign visits, to India and the Gulf respectively, to drum up support and investment for Britain from countries outside the EU.
During his trip to Delhi, Mr Hammond said he was "ambitious to do a free trade deal with India as soon as we can."
However, in an interview with Sky News, Mr Hammond was asked seven times whether his department had attempted to calculate the economic impact of the Government not reaching a deal with its European counterparts.
Mr Hammond said "we are looking at the possible range of outcomes", but refused to answer specifically whether his department had carried out work analogous to the forecasts it famously made before the referendum.
It comes amid growing concern that the UK authorities have sacrificed economic priorities in favour of cutting immigration and loosening ties with Europe.
The pre-referendum analysis produced by the Treasury suggested households would be around £2,000 a year worse off by 2030 if the UK left the single market than if it stayed inside.
Mr Hammond also admitted that last month's u-turn on raising national insurance contributions for self-employed workers had underlined the difficulty of making economic policy against the backdrop of the last election's manifesto promises.
He said: "The 2015 manifesto contained a lot of commitments around tax and spending that have made the room for manoeuvre for a Chancellor very limited.
"They've very significantly limited the scope that a Chancellor normally has. But we've accepted that that's something we will live with.
"We will not necessarily be able to renew all those commitments. We'll look at them in due course before the next general election."