Downing Street staff are braced for questions from police as detectives investigating lockdown parties in No 10 begin contacting those believed to have been involved.
Scotland Yard said by the end of the week officers from Operation Hillman will have started sending out formal legal questionnaires to more than 50 individuals.
The events under investigation include a number known to have been attended by Boris Johnson, raising the prospect that he will be among those receiving a demand for answers in their inboxes.
