Boris Johnson paid tribute to Allegra Stratton during a Downing Street press conference tonight.
The Prime Minister implemented Plan B measures on Wednesday night, with people told to work from home and the NHS covid pass set to become mandatory.
The press conference came just hours after Downing Street advisor Allegra Stratton resigned over a video of her laughing and joking about an alleged Christmas party that took place at Number 10 last year.
READ MORE: NHS covid pass mandatory for nightclubs and other venues as Plan B brought in
BBC Political Editor Laura Kuenssberg quizzed the Prime Minister and asked him how he could ask people to follow restrictions after his own team had "laughed and joked at that same lecturn".
Mr Johnson said: "The first thing I want to say is that I know today that Allegra Stratton has resigned and I wanted to pay tribute to her.
"She has been, in spite of what everyone has seen, again I make no excuses for the frivolity with which the subject was handled in that rehearsal that people saw in that clip.
"There can be no excuse for it and I can totally understand how infuriating it was, but I want to say that Allegra has been a fine colleague and has achieved a great deal in her time in government and was particularly an effective spokesman for Cop26.
"She helped to marshal and rally the world in Cop26 and Laura you'll have to forgive me I wanted to say that."
Ms Stratton resigned earlier this afternoon and said: "My remarks seemed to make light of the rules everyone. That was never my intention.”
"I will regret those remarks for the rest of my days and offer my profound apologies to all of you for them.
"Working in government is an immense privilege. I tried to do right by you all, to behave with civility and decency and up to the high standards you expect of Number 10.
"To all of you who lost loved ones, who endured intolerable loneliness and who struggled with your businesses, I am truly sorry.”
