David Walliams's MUM guest judges Britain's Got Talent 2016 tonight - and BUZZES all the acts!

Kathleen Williams pulls no punches as she stands in for Simon Cowell

David Walliams' mum Kathleen Williams stands in for Simon Cowell on Britain's Got Talent 2016

David Walliams' MUM Kathleen Williams fills in for Simon Cowell in tonight's Britain's Got Talent 2016 auditions - and proves to be harsher than even Mr. Nasty himself.

The often tardy media mogul was so late for one filming session in London that hosts Ant and Dec had to tell the audience: "We’ve got some bad news for you this afternoon - Simon Cowell is not here at the moment, but he’s gonna try and make it in."

The short notice meant bosses didn't have time to book Louis Walsh as a guest judge - but David had his own replacement.

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"I think we really need someone to fill that seat," he said. "My mother is here today. She’s gonna be Simon if she doesn’t mind!"

As Kathleen sat down at the desk, David joked: "I’m sure Simon wouldn’t mind if you used his Golden Buzzer!"

David Walliams’ Mum Kathleen Walliams
David Walliams’ Mum Kathleen Walliams replaces Simon Cowell.

However, it turned out that she didn't need it - as she ended up buzzing off almost every single hopeful that she saw.

Kathleen blasted one act as "sweet, but not very exciting", and told another: "It was nice music ruined by stupid movements."

Shocked by how "harsh" she was being, Ant and Dec went out to ask if there were any talents she specifically wanted to see - but there were no male singers with their tops off to hand.

"You've got a dark side, mum!" laughed David. " I think Simon’s spirit has entered you!"

A suspicious Amanda Holden added: "She’s taken to it like a duck to water. I reckon Simon's actually here judging us judging!"

Fortunately, the Geordie duo did manage to find something that impressed Kathleen - but you'll have to tune in to Britain's Got Talent tonight at 8.00pm on ITV to find out what it is.

Simon fans needn't fret as he does eventually show up - only to put his life on the line by getting involved in a daredevil CROSSBOW stunt.

Browse pictures of the latest BGT auditions below: