Johnny Mercer has compared Labour’s new MP for Selby and Ainsty to an “Inbetweener” as he made a jibe over his age.

Keir Mather, 25, became the ‘Baby of the House’ – the youngest member of the Commons – overnight as Labour secured a historic victory in the Yorkshire seat.

The party overturned its largest ever majority at a by-election, winning by more than 4,000 votes. The Tories won Selby and Ainsty with a majority of 20,137 at the last general election.

Mr Mercer mocked Mr Mather over his age during an interview with Sky News to discuss Thursday’s results, which saw the Conservatives also lose in Somerton and Frome but keep Boris Johnson’s old seat of Uxbridge and South Ruislip.

The veterans’ affairs minister said: “I think it’s always good to get new people in politics. I think we mustn’t become a sort of repeat of The Inbetweeners, right?”

Challenged on what he meant by that, he replied: “You’ve got to have people who’ve actually done stuff. This guy, you know, has been to Oxford University more than he’s been in a job.

“You put a chip in him there, and he just relates Labour lines. And the problem is people have had enough of that, right? They want people who are authentic, people who have worked in that constituency, who know what life is like, who understand what life is like, to live, work and raise a family in communities like theirs.

“So no, I’m afraid I don’t agree with this style of politics. It’s exactly why people like me didn’t vote for the 2015 general election.”