As they went to leave Nancy went off to the toilet without telling them.
The Prime Minister was driven back to Chequers, which is two miles from the pub, with protection officers in one car, while Mrs Cameron drove their other children in another.
Mr Cameron presumed that Nancy was in the car with his wife, while she thought that their daughter had jumped in with the Prime Minister. A spokesman for the Prime Minister last night said he was ‘distraught’ when he realised what had happened.
‘Thankfully when they phoned the pub she was there safe and well,’ the spokesman said. ‘The Prime Minister went down straight away to get her.’ When Mr Cameron arrived back at the pub he found his daughter happily helping the pub staff.
It is understood she had been left by herself for 15 minutes. Last night a pub ‘insider’ said: ‘You’d have thought that someone would have done a headcount or something.’