Top civil servant could become third key No 10 departure in days

Exclusive: Cabinet secretary Chris Wormald is expected to follow Morgan McSweeney and Tim Allan out the door

The most senior civil servant in Downing Street is negotiating his exit as part of a wider shake-up of Keir Starmer's operation after one of the most dramatic 48 hours of the prime minister's time in office, sources have told the Guardian.

Chris Wormald, the cabinet secretary, is understood to be negotiating the terms of his departure from No 10, which would make him the third senior member of staff to leave in recent days.