Oliver Robbins, the prime minister’s chief civil service Brexit negotiator, has been offered jobs in the city and plans to jump ship with some of his top team.

Senior government sources claim Robbins already has an informal arrangement with a merchant bank for a lucrative new role once Brexit happens next spring. Officials in the Cabinet Office and Department for Exiting the European Union say Robbins has also had informal discussions with members of his team about joining him in the private sector.

As the key official on Brexit with a detailed understanding of every regulatory issue, Robbins is expected to command a salary that could top £1m in the City. But any new job would be scrutinised by the advisory committee on business appointments,