Downing Street's cat - and official rodent catcher - Larry has been spotted asleep on the job for several hours.
The tabby was brought to No 10 to tackle the rat problem, but on Monday it emerged that a mouse had appeared at a recent prime ministerial dinner.
The PM's spokesman rebuffed calls for Larry to resign, saying he "brings a lot of pleasure to a lot of people".
The BBC's Norman Smith said the arrival of the entire cabinet had not woken him from his slumber on a hot air vent.
He tweeted that photographers arriving at Downing Street for a press conference were initially ordered not to take shots of Larry asleep by the famous black door.
However, aides eventually backed down and said the cat could be pictured.
Norman Smith, the BBC News Channel's chief political correspondent, said Larry was asleep when he arrived outside No 10 just before 0800 GMT on Tuesday and showed no signs of waking up, even when one minister after another arrived for the weekly cabinet meeting.
'Threw a fork'
Four-year-old Larry came to Downing Street from Battersea Dogs and Cats Home in February after a large rat was seen scuttling past the door of No 10 during live television broadcasts.
He was said to have "a very strong predatory drive", developed during his time on the streets.
In June, David Cameron told the BBC he was "a good mouser" and had caught three mice since his arrival.
But it has emerged that the PM resorted to throwing a fork at a mouse last week when it was spotted during a dinner with cabinet ministers.
He had earlier seen a mouse in his kitchen during another dinner with family - although he insisted at the time that Larry had not yet been allowed into that room.
There have been suggestions that Larry spends more of his time asleep or with a lady friend, Maisie, than he does hunting rodents.