Whitehall leak means hard Brexit "dead in the water" says Nicola Sturgeon

“Theresa May must face down the hard Brexiteers around her and put jobs and living standards front and centre of the Brexit negotiations by remaining in the single market and customs union.”

Ms Sturgeon insisted that the Whitehall report now must be published in full.

But Whitehall, seeking to play down the leak, refused.

The Prime Minister raised the matter at the start of the weekly Cabinet meeting in Downing Street, telling colleagues that the document "purported to show" the economic impact of various Brexit scenarios. No other minister spoke on the leak.

No 10 later stressed how the report was an incomplete draft, was “not signed off” by ministers and did not address the bespoke deal the Government was seeking.

The leak to the BuzzFeed News website suggested even if the UK were able to negotiate a comprehensive free trade agreement - as Mrs May hopes - it estimated growth would be down five per cent over the next 15 years.

This would rise to eight per cent if Britain left without a deal and was forced to fall back on World Trade Organisation rules.

Alternatively, if the UK were to retain access to the single market through membership of the European Economic Area, the loss would be just two per cent.

In the Commons, an Urgent Question was granted, forcing a minister to the Despatch Box; it led to acrimonious exchanges.

Steve Baker, the Brexit Minister, suggested it was not in the national interest to release what was an incomplete assessment, not seen or approved by ministers, while negotiations with Brussels continued.

He described the document as a “selective interpretation of a preliminary analysis” and claimed: “It is an attempt to undermine our exit from the European Union.”

But Sir Keir Starmer for Labour replied: "Not good enough."

The Shadow Brexit Secretary urged the Government to release the information showing the impact of Brexit, accusing it of "piling absurdity upon absurdity".

Mr Baker hit back, claiming Labour was "completely neglecting" its duty to protect the national interest during the Brexit process.

"They care passionately about remaining in the European Union and they want to overturn the result,” he argued, describing Mr Corbyn’s strategy as one of “demoralisation, delay and revocation”.

Kenneth Clarke, the Europhile former Conservative Chancellor, accused ministers of trying to protect the Government from "political embarrassment" in refusing to release the leaked document in full.

Fellow Tory backbencher Antoinette Sandbach said: "I take exception to being told it is not in the national interest for me to see a report that allows me to best represent my constituents."

Labour’s Chris Leslie accused the Government of a "cover-up," telling MPs: "For the minister to basically use the excuse of not publishing this because he hasn't yet had the chance to edit it, twist it, distort it, redact the information within it, is a total and utter disgrace.”

Today during a Commons debate and vote, Labour will today try to force the Government to release the Brexit impact assessment in full, using the same archaic parliamentary procedure it adopted last year to coerce ministers to release Brexit impact papers to a Commons committee.

Sir Keir said: "Ministers cannot keep side-lining Parliament to hide the deep divisions within their own party. They should accept this motion and allow the country to have an informed debate about its relationship with Europe after Brexit."

Meanwhile, Mr Baker also incurred the wrath of civil servants after he suggested they had produced a sub-standard piece of analysis; Whitehall forecasts were "always wrong," he said.

Dave Penman for the FDA union of top officials, denounced the minister’s remarks, saying they “not only insult the dedicated professionals working in his department and across the civil service but they epitomise the current state of affairs in government”.