An influential group of MPs has warned against Theresa May's plan to set up a dedicated "Ministry for Brexit", saying it could lead to "rival power structures" and pointless duplication emerging in Whitehall.
May, who becomes Britain's new prime minister on Wednesday, has vowed to set up a department dealing with Brexit issues, to be headed up by a Cabinet minister. It is expected that the new secretary of state will be among the first names announced when May begins unveiling her new-look Cabinet today.
The plan for a fresh department marks a significant step-up from the current, cross-government team of officials set up in the wake of the UK's vote to leave the EU. That team, headed up by permanent secretary Olly Robbins, is housed in the Cabinet Office and will also draw on the support of experts from the Foreign Office, Treasury, Department for Business, Innovation and Skills.
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But in a letter requested by Cabinet Office minister Oliver Letwin, who was handed political control of the unit, the Public Administration and Constitutional Affairs Committee (PACAC) raises the lessons of history to question the validity of May's plan.
PACAC points out that when Whitehall prepared for the UK to join the EU's forerunner – the European Communities (EC) – in 1970-71, a Cabinet Office minister was given a seat at the Cabinet table and handed responsibility for coordinating accession talks "across all government departments".
This, the committee says, allowed the prime minister to be "closely involved in the negotiations and preparations for EC membership", and helped "all departments to think and act European" – without giving rise to conflicts between different parts of Whitehall.
"The possibility of a new Ministry for Europe was discussed but not seriously considered," the MPs says. "Either it would have had to be given such extensive powers over other government departments, with the potential for conflicts at the centre, or it would too easily be marginalised. It was also felt that a lead department such as Treasury or FCO would never be wholly trusted to be impartial with the rest of Whitehall."
PACAC says the arguments against creating a dedicated Europe department "are just as applicable to a Department for Brexit today", saying that leaving the EU represents a "whole-of-government project" and must not be hived off into a separate department.
"The prime minister, supported by the cabinet secretary as head of the civil service, must be able to provide overall leadership to both the civil service, and to the Cabinet, to provide oversight and to approve key policy decisions," the committee adds.
"No other arrangement could provide as effectively for these key elements."
The commitee says any minister put in charge of leading the government's withdrawal from the EU should take charge of the existing Cabinet Office Brexit unit, and work to "coordinate officials and ministers across Whitehall".
"This approach avoids duplication, and puts the new prime minister with the cabinet secretary in overall control of policy and process," they add. "It would also remove the risk of rival power structures, by providing a clear chain of political authority, while the Brexit unit in the Cabinet Office can optimise policy and resource coordination across Whitehall."
PACAC's warning comes after the Institute for Government think tank voiced its own reservations about May's idea, using a new report to warn of the "time, cost and distraction that would inevitably come from creating an entirely new organisation".
The report's authors, Julian McCrae and Jill Rutter – both former senior officials who have worked at the heart of government – said that while a new ministry of Brexit could provide a "durable, long-term home" for a minister handed wider Brexit policy responsibilities, such as trade, there were "serious operational drawbacks" in creating a unique department.
"New departments should only be created where there is an irrefutable business case that this is the best option and adequate advance planning has been undertaken," McCrae and Rutter said.
Shadow civil service minister Louise Haigh meanwhile cautioned against launching "introspective and cross-departmental reorganisation" when officials "should be focussed on getting the best possible deal for Britain".