David Cameron jokes new Labour MP should 'keep her mobile on' in case of Shadow Cabinet job on her first day

Jeremy Corbyn has faced mass resignations from his Shadow Cabinet since the Brexit vote

Dr Rosena Allin-Khan laughs as David Cameron jokes she could be a Shadow Cabinet minister by the end of her first day as an MP (BBC News)

David Cameron has joked that the new Labour MP for Tooting should “keep her mobile on – she might be in the Shadow Cabinet by the end of the day” as the Prime Minister gave his statement to MPs about the Brexit referendum result.

The remark sparked widespread laughter with Labour leader Jeremy Corbyn facing mass resignations from the Shadow Cabinet over his handling of the Labour In campaign.

Dr Rosena Allin-Khan, elected to replace the new Mayor of London, Sadiq Khan, was sworn in as a Labour MP in front of a packed House of Commons just moments before Mr Cameron gave his statement.

She and other MPs smiled broadly as she swore allegiance to the Queen then stood near the Speakers’ chair.

“Let me welcome the new member for Tooting to her place,” Mr Cameron said to cheers from both sides of the House.

“I think I’d advise her to keep her mobile phone on – she might be in the Shadow Cabinet by the end of the day.”

Dr Allin-Khan smiled broadly amid the general laughter, not joined by Mr Corbyn who remained looking serious with his head bowed.

“Lots of vacancies coming up!” someone shouted.

“And I thought I was having a bad day,” Mr Cameron added to renewed laughter.