THE Chase star Mark 'The Beast' Labbett only discovered he had married his cousin AFTER their fairytale castle wedding.

Mark and Katie had their marriage thrust into the spotlight this weekend after The Sun revealed the quiz guru's 26-year-old wife had cheated on him.

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The 53-year-old telly favourite and Katie, the mother of his young son, was completely unaware when they began dating that they were actually second cousins.

Teacher-turned-star Mark made the shocking revelation in an interview after the couple had been married for over three years.

Katie’s dad and Mark's father are first cousins, making them second cousins.

Mark said of the unusual connection: "It wasn't something we were aware of at the time - it was one of those things that happened."

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He told the Loose Women panel: "I had been a single man for a long while so I was getting used to the idea of being on my own.

"Especially as a bachelor, we can get pretty selfish, you get used to doing what you want to do all of the time.

"As a couple of my friends pointed out the big challenge for me is learning to adapt with being with someone else."

The pair tied the knot more than four years ago after meeting through mutual friends.

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Oxford-educated Mark married Katie at Arundel Castle in West Sussex in October 2014.

Over the weekend The Sun told how Katie, 26, had been cheating with a local man 25 years Mark’s junior.

We revealed how she had holidayed with a 28-year-old hunk called Scott Bate behind her famous husband's back.

A source explained that Katie has been dating him for well over a year, saying: "Scott and Katie have been seeing each other since 2017. He introduced her to friends in December that year.

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“It took a while for people to realise who she was and that she was married. Then one of Scott’s friends confronted her and she got angry about it.

“She appeared on Loose Women with Mark and people started sending a clip around when they twigged who she was.

“People don’t think it’s right and think her behaviour is unfair on Mark — and Scott.”

Clues to Katie’s apparent ­double life appeared on the Facebook page of metals firm worker Scott. His profile picture was Katie with her arm around his neck.

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Snaps showed them at a beer tasting, in front of a waterfall at the Watersmeet National Trust park in Devon and on a train on a separate day out.

On Valentine’s Day in 2018, Scott shared a picture of them on a night out the previous evening. He told a pal: “We did it a day early so it’s not as busy.”

After being approached by The Sun, Scott removed pictures and mentions of Katie from his Facebook page.

He said it was “no surprise” that his relationship with Katie was being talked about in Hereford. But he added: “I don’t want to comment. You will have to speak to her about it.”

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Katie refused to answer the door at the detached cottage she shares with Mark two miles away.

A spokesman for Mark — who has appeared on US and Australian versions of The Chase — declined to comment.

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