If you walk along Whitehall on one of these cold, dark autumn evenings and look up, you see the lights burning late in one civil service office after another. Officials in every government department are engaged in an analytical exercise unprecedented in its scale, scope and complexity as they prepare for Britain's departure from the European Union.
Their task is to map the entire British economy, sector by sector, and by sub-sector, region by region, and in some cases town by town. By the end of the year, they will have a granular picture of the implications of Brexit for every part of the economy.
“Most of Whitehall is probably working on this in one way or another,” said one senior official at the heart of the process.
Seven steering boards are directing the mapping exercise, which involves officials in every department. In some, such as the department of the environment, food and rural Affairs, almost everyone is working on Brexit.
Mapping
The purpose is not just to prepare ministers for the formal exit negotiations which will begin next spring, but also to identify the systems a post-Brexit Britain will have to set up or restore. Parallel to the mapping exercise, officials are examining the implications of leaving the EU for issues of justice, security and civil law.
This involves everything from rules governing wills and contracts to information sharing on criminal gangs and shared databases of fingerprints and DNA samples.
A third strand of the exercise concerns questions around the devolution to Edinburgh, Cardiff and Belfast of some of the powers which will be repatriated from Brussels. All of this analysis will inform the drafting of the Great Repeal Bill, which will repeal the 1972 European Communities Act and transpose EU law into British law.
Whitehall sources point out that much EU law cannot be directly transposed because it involves issues such as the competent authority for policy areas.
British officials are operating on the basis that the two-year deadline for exit negotiations under article 50 of the Lisbon Treaty will not be extended, partly on account of the electoral timetable, with European Parliament elections due in the summer of 2019 and a British general election scheduled for 2020.
At the end of two years, the two sides should have negotiated a withdrawal treaty, which is likely to cover some of the institutional and budgetary issues around Britain’s exit. Whitehall hopes it will also set out transitional arrangements for policy areas which will require further negotiations, including Britain’s future trade relationship with the EU.
The scope of negotiations under article 50 and of any withdrawal treaty will itself be a matter for negotiation with Britain's EU partners. Noises from Brussels suggest that the European Commission is inclined towards a narrow negotiation, which may not include any provision for transitional arrangements.
Without transitional arrangements, the relationship between Britain and the EU will, in the words of one Whitehall source, "fall off a cliff" in early 2019. If a withdrawal treaty is agreed, it must be approved by a qualified majority in the European Council, receive the assent of the European Parliament and almost certainly parliamentary approval in Westminster.
Immigration
Although much of the commentary about Brexit in
Europe
has focused on the future of free movement of people between the EU and Britain, British officials suggest that immigration policy may not be up for negotiation at all. The promise to “take back control” of immigration was so central to the referendum campaign that many in Whitehall believe it could be politically unacceptable to engage in negotiations over it.
Instead, Britain could inform its EU partners of how it plans to control immigration from the EU after Brexit, perhaps with a system of work permits. There is no appetite in London for introducing a visa requirement for EU citizens visiting Britain. If Britain does announce in advance of negotiations its intention to restrict immigration from the EU, the other EU member states will almost certainly remove from the table the possibility of Britain remaining in the single market after Brexit.
The hope in Whitehall is that a withdrawal treaty with transitional arrangements will ensure the smoothest possible exit from the EU, with no shocks or sharp edges. Officials acknowledge, however, that the best-laid technocratic plans can go off the rails very fast as soon as they confront political sensitivities, both in Britain and in the rest of Europe.