The Department for Exiting the European Union, which employs nearly 600 people, has a high staff turnover

Britain’s departure from the European Union is being driven by millennials, with only two in ten civil servants working on Brexit able to remember a time when the UK was not in the bloc.

An analysis of government personnel data reveals that the average age of staff at the Department for Exiting the European Union (Dexeu) is 31, with 83 per cent of officials under 40.

Oliver Robbins, the government’s chief Brexit negotiator, was born two years after Britain joined the European Economic Community in 1973.

The figures from the Institute for Government show that Dexeu, which was set up after the EU referendum and now employs nearly 600 civil servants, has relied heavily on young graduates to fill its posts. Insiders say that the