David Davis, the secretary of state for exiting the European Union, attended a seminar at Oxford University last month that drew up a blueprint for hard Brexit, the term describing Britain’s total departure from the bloc.

The seminar at All Souls college on 9 September was also attended by leading pro-Brexit MPs, legal and trade experts who broadly support a hard Brexit from the EU, and senior civil servants.

The group proposed the ”great repeal bill” set out on Sunday by Theresa May, the prime minister, as well as an early triggering of article 50, the clause that starts the two-year timetable for the Brexit negotiations. May has announced that it will be triggered by the end of next March.

The discussions at the seminar have been condensed into a pamphlet published jointly by the Centre for Social Justice and Legatum Institute, two thinktanks likely to be at the heart of setting out the Conservative case for a hard Brexit.

Davis has insisted he is consulting widely, but his involvement at the seminar underlines the closeness of his contacts with leading Eurosceptic MPs such as John Redwood, Iain Duncan Smith and Peter Lilley.

Allies of Davis said he had attended to observe and did not speak at the seminar. They also stressed he did not endorse the conclusions of the Legatum report.

Those conclusions bear a remarkable resemblance to the government’s work on Brexit to date, and the attendance of such high-ranking figures as Davis suggests it will continue to remain influential.

The summary published last week states the seminar “concluded that the government should now make due haste with sending an article 50 letter and introducing a repeal bill for the 1972 European Communities Act”.

It adds: “The country and business wish to reduce the uncertainty.” The seminar “was swayed by a survey of larger businesses and by the business debate into seeing the need for speed, and the opportunities that flow from exit”.

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The report says the seminar “was persuaded that leaving the EU is primarily a UK parliamentary process, repealing the 1972 act and renewing EU law as UK law to ensure continuity.

“There was general agreement that this is best done by means of a short general principles and powers bill, mirroring exactly the short legislation of the 1972 act to impose the EU legal authority in the first place.”

The seminar also concluded that legal proceedings due to start soon intended to produce a court ruling that would force a parliamentary vote on the triggering of article 50 would not succeed. The report suggests: “The best course could be to pass a Commons motion in support of a letter and to send it as soon as possible, whatever the state of the legal proceedings.”

It also suggests May should explore what kind of future trading relationship the EU commission seeks with the UK, suggesting the issue is largely for the EU to determine.

It says the conference “was sympathetic to the view that the trade negotiations can be short and simple. The UK can offer either to carry forward current tariff-free trade with service sector passports, or to fall back on the World Trade Organisation standard-tariff trade. The UK would recommend the former, but could live with the latter. Rather than negotiate, it is just a question of which the rest of the EU will choose.”

It concludes “Whilst the EU commission is likely to threaten the imposition of WTO rules, the member states are likely to opt for the status quo of tariff-free trade given business lobbies in their own countries.

“The balance of trade and tariff rates under WTO rules is more damaging to the rest of the EU than to the UK, given the UK’s bias to services which are all tariff-free, and given the devaluation of the pound which has already made rest of the EU products less price-competitive without extra tariffs.”

The report on the conference gives an optimistic assessment of the balance of forces on trade talks, stating: “It was also confirmed that the UK remains a member of the WTO, and establishing the same or a new tariff schedule with the WTO for trade with the EU would be easy, given we would be taking either our current tariff-free approach or the standard EU rest of the world tariff schedule.

“What takes time in international trade is negotiating a new deal between two countries with substantial barriers, which is the opposite of the case of the UK/EU where all tariff barriers have been removed.”

All Souls said it was neutral on the issue of Brexit, and was simply hosting the discussion.