THE road to a hard Brexit risks leaving Britain with the “worst of all worlds” and no deal at the end of two years of talks, pro-EU former ministers have warned, as Theresa May prepares to trigger Britain’s historic departure from the Brussels bloc after 44 years’ membership.

On Wednesday after PMQs, the Prime Minister will give a Commons statement, setting out how she proposes the two-year process of withdrawal will unfold and what her Government’s aims and priorities are.

At the same time, Sir Tim Barrow, the UK’s Permanent Representative to the EU, will hand over a letter to Donald Tusk, the President of the European Council of EU leaders, formally invoking Article 50 of the 2007 Lisbon Treaty.

It will be the first time any member of the EU has asked to leave, so the detailed process ahead is somewhat unknown.

Nick Clegg, the former Deputy Prime Minister, Nicky Morgan, the former Conservative Education Secretary, and Chris Leslie, the former Shadow Chancellor, said tomorrow the “phoney war” over Brexit would finally be over.

Speaking in a joint statement under the auspices of the Open Britain pressure group, which campaigns for retaining the closest links to the EU, the three former frontbenchers said, as "realists", they feared Mrs May's plans for withdrawal would not deliver the outcomes promised by the UK Government and the Vote Leave campaign in last year's referendum.

They said there was "no mandate for the form Brexit takes" but noted how "a clear direction of travel” had been set by the Government largely based the Vote Leave campaign’s aims.

The three senior MPs explained: "Vote Leave and the Government have made specific promises: leaving is a cost-free option; trade will be enhanced not hampered; there will be major savings from the EU budget; core arrangements with the EU, for example over national security, will remain unchanged; and the integrity of the United Kingdom will be protected.

"Now that Article 50 is being triggered, people will expect these promises to be delivered: this is the Government's Brexit contract with the British people,” they declared.

But they said political choices had been made by the PM, which “potentially undermine these ambitions and which make the path ahead riskier than necessary".

They warned that if the "Brexit contract" of promises could not be honoured, then "it increases the chances of the UK leaving the EU with no deal at all,” which would be “the worst of all worlds".

The MPs added: "As patriots, we want the best for our country. As realists, we fear the Government's Brexit contract may not deliver that outcome. And as democrats, we think that should be a judgment people and Parliament are able to make."

Today, a survey of 150 MPs by Comres, which is establishing its own Brexit unit to help organisations “navigate the Brexit landscape”, found: nine in ten MPs expected the UK to leave the European single market; six out of ten expected the UK would leave the EU’s customs union; two-thirds thought, post Brexit, the UK would remain formally associated with Europol; seven in ten MPs believed net migration would fall and more than eight in ten expected the UK to prioritise skilled migration over unskilled migration from the EU.

Meantime, No 10 seemed to back away from the suggestion made by David Davis, the Brexit Secretary, who claimed Britain could secure the “exact same benefits” in a negotiated deal as the country enjoyed from membership of the single market and customs union. A Downing Street spokesman insisted Mrs May’s aim was to get the “greatest possible access” to the single market through a comprehensive free trade deal.

In other developments:

*Sir Keir Starmer, the Shadow Brexit Secretary, urged the PM to "face down" hardline Brexiteers in her own Government, who risked taking Britain into a "disastrous and divisive" new reality following withdrawal;

*Paul Nuttall, the Ukip leader, said his party did not need any Commons representation to influence Brexit following the resignation to go independent of its sole MP Douglas Carswell and that Ukip would now be the "guard dogs" of the withdrawal process while

*Sadiq Khan, the London Mayor, during a three-day visit to Brussels, said Brexit must not be allowed to damage security co-operation with the EU in the wake of the Westminster terror attack.