
He asks how the civil servant who Sir Gavin reportedly told to "slit your throat" felt when Mr Sunak said he accepted the resignation "with sadness".
Mr Sunak says it is "right" that Sir Gavin resigned, but says "for the record, I did not know about any of the specific concerns".
Sir Keir asks if Mr Sunak regrets the decision to appoint Sir Gavin.
The PM says he "obviously regrets" appointing someone who has had to resign in these circumstances.
And Mr Sunak is jeered by the opposition as he says his government will be "characterised by integrity, professionalism and accountability".
Sir Keir likens Sir Gavin to a "sad middle manager who gets off on intimidating those beneath him", and says Mr Sunak is a "boss who is so weak, so worried the bullies will turn on him that he hides behind them".
Everyone in Britain knows people like this, says the Labour leader, who has a spring in his step.
In response, Mr Sunak repeats that it is "right" Sir Gavin resigned - "the message that I clearly want to send is that integrity in public life matters".
Read up-to-date coverage:
Subscribe to The Telegraph with our special offer: just £1 for 3 months. Start your free trial now:
Get the latest headlines:
Telegraph.co.uk and YouTube.com/TelegraphTV are websites of The Telegraph, the UK's best-selling quality daily newspaper providing news and analysis on UK and world events, business, sport, lifestyle and culture.