At Chequers, the Prime Minister must stick to her "no deal is better than a bad deal" mantra, or risk splitting the Conservative Party like Sir Robert Peel

The Prime Minister said, as soon as she took office, that “Brexit means Brexit” and in the last election, in her personal contract with the British people, she declared that we would leave the single market and the customs union. At Chequers this week the nation will see if her promises are kept or if the policy advocated by a former member of the SDP wins favour.

The Prime Minister’s greatest virtue is her dutifulness, without a Parliamentary majority and with a cabinet that has forgotten Lord Melbourne’s definition of collective responsibility “it is not much matter which we say, but mind, we must all say the same”, nonetheless she carries on.

Perhaps the vicar‘s daughter is inspired by the hymn “Jesus good above all other, gentle child of gentle mother in a stable born our brother, give us grace to persevere”. It is certainly a grace she has been given in abundance and it is also her great strength.

As the cabinet prepares to assemble in the Buckinghamshire countryside it may choose to reflect on what we have already done and it should consider what unity and determination can deliver.

The European Communities Act will be repealed next March. The country is now leaving the EU in its own domestic law, just as the UK was already leaving the EU in international law under the relevant treaties.

The United Kingdom has irrevocably set a new course. One where the nation will be free to make its own laws and conclude its own trade agreements, free to take back control of its immigration policy and no longer obliged to pay “Eurogeld” in return for the dubious privilege of following EU laws.

The question for the Cabinet at Chequers is what to do with the freedom the British people want reinstated. Does it seize this great opportunity to do things better, to forge new trade relationships, to have better laws, regulations and policies or does it follow the managers of decline to place a once proud country in a tremulous state that sees Brexit as mere damage limitation?

This is a historic decision and one the Prime Minister is well placed to make. Theresa May has the vision and has put the law in place to leave the EU. However, there are political challenges ahead.

There is a need to overcome fear of the future. In leaving the EU the UK will have a new relationship with it based on trade without political convergence. Trade between two friends and partners who respect each other’s internal legal authority. This is the case for the majority of world trade. Yet there are still those who advocate the vassal state with the UK accepting the domestic application of EU laws as a price of trade: something no other trading partner agrees to.

Then we need to call the Irish bluff. There is no insurmountable problem concerning the Northern Ireland border and any solution which would split the UK in two is outrageous. That the EU suggested it is offensive.

Ireland is being used by the EU credit: Clodagh Kilcoyne/Reuters

This fake alarum should be seen for what it is: domestic Irish politicking in advance of a general election with Dublin being gullibly exploited by Brussels.

The Irish government, if not the European Commission, thought that Dublin had “cast iron guarantees” which suited them last December, then again last March and had hopes finally of getting them in June. They have been disappointed each time by their friends on the continent.

Ireland is being used by the EU to put pressure on us. Her Prime Minister supporting Belgium over England might get cheered in Irish pubs but it is not getting them anywhere in Brussels.

What ought the Cabinet to decide on Friday? Above all it must maintain the clear negotiating line set out at the beginning: no deal is better than a bad deal, and plenty of bad deals are on offer.

Fortunately, David Davis with his titanium plated spine and his ministers in DExEU have ensured that preparations for a “no deal” scenario are well advanced. There can be no sensible argument that we have to take a bad deal because a “no deal” outcome has not been prepared for. This is simply incorrect, primarily thanks to Steve Baker.

The Cabinet should agree that if there is to be a deal it has to be agreed in detail prior to our departure. There is no legal reason to pay £39 billion to the EU on our departure and if there were no guarantee of a trade agreement it is something I would strongly oppose in any vote in the House of Commons. Likewise leaving the EU into the purgatory of a perpetual transition would be foolish.

If a bad trade agreement should be rejected, what exactly is a respectable one? It must be judged against the UK’s economic interests but there are some things that no independent nation could agree to. Any attempt by the EU to impose its laws and Court on the UK, either directly or indirectly, must be rejected. Any EU agreement that restricts the country’s ability to make trade agreements with other states, restricts our ability to control our migration policy, makes us pay to trade or interferes with our fishing waters could not be accepted.

Indeed many MPs would vote against such propositions if brought to Parliament. In this regard, Michael Gove was right to tear up any form of the idiotic customs partnership.

The Prime Minister commands the support of Brexit backing Members of Parliament, Conservative party members and Brexiteers in the nation at large. This is why her opinion poll ratings remain so high. Yet the metropolitan establishment of fashionable society and the beau monde is still against her. Theresa May must stand firm for what she herself has promised.

One former Tory leader, Sir Robert Peel, did decide to break his manifesto pledge and passed legislation with the majority of his party voting the other way so leaving him dependent on opposition votes. This left the Conservatives out of majority office for twenty-eight years, 1846 to 1874. At least he did so for a policy that worked.

At Chequers the Prime Minister must stick to her righteous cause and deliver what she has said she would, she must use her undoubted grace to persevere.

Jacob Rees-Mogg is Conservative MP for North East Somerset and chairman of the European Research Group