An influential committee of MPs has called upon an official at the department for business to answer questions on the EU following the publication of his award winning essay on Brexit.
The group of MPs on the Treasury Select Committee want to see the civil servant, Iain Mansfield, who wrote the essay on how Britain could leave the EU.
As such, Andrew Tyrie, chair of the committee, has written to Sir Jeremy Heywood, the UK's most senior civil servant, asking him to set a date for Mansfield to answer questions on the EU debate.
"The views of Mansfield matter. He has offered one of the few detailed assessments of the impact of "Brexit"on the UK economy," Tyrie said.
"Mansfield provided his assessment in a personal capacity and, having obtained permission. The government’s internal guidelines on this, the so-called Osmotherly Rules – to which the Prime Minister alludes – do not apply in such cases. The committee would like to hear from him."
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The Prime Minister has been joined by the foreign secretary and the business secretary, all of whom have declined the committee’s request for Mansfield’s appearance, arguing that it would be in breach the Osmotherly Rules.
Mansfield has consistently refused to arrange a date on the basis that the Osmotherly Rules prevent officials from giving evidence in a "personal capacity".
In 2014 Mansfield won the Institute of Economic Affairs Brexit Prize for his essay A Blueprint for Britain – Openness not Isolation. At the time, he was working as the director of trade and investment at the UK’s embassy in the Philippines.
The essay contains detailed views about how a "Brexit" should happen and the impact that it would have on the UK economy.
The essay said: "Exiting from the EU should be used as an opportunity to embrace openness. The UK should pursue free trade agreements with major trading nations such as China, the USA and Russia and deepen its engagement with organisations such as the G8, G20 and OECD."
"In Europe, a priority must be to secure open trade relations, ideally by membership of the European Free Trade Area, though remaining outside the European Economic Area. Bilateral strategic relationships with allies such as Australia, Canada and France, as well as emerging powers in Asia and Latin America, should be cultivated.
"Measures such as tax breaks and supply-side incentives would help preserve the UK’s position as the number one inward investment destination in Europe."