Channel 4's Countdown in major shake-up as Rachel Riley replaced by tattooed YouTuber

Fans of Countdown are to see a big change to proceedings with Rachel Riley not in her usual role.

Instead, a YouTuber has taken over the reins. Dr Tom Crawford, who is known for his channel in which he teaches sum in his underwear, is standing in for the mathematician who is currently working on another project.

He is a pal of the star and is said to have been shown the ropes by her ahead of his own stint. The 35-year-old has over 200,000 subscribers on his own channel, in which he describes his goal of making "elite mathematics teaching available to everyone".

Speaking of her friend's new role, Rachel joked: "[Crawford] is used to people commenting on the clothes he wears – or lack of them – on his show, so I am sure he will take to the role like a duck to water."

Tom started filming for the sow in December. He's set to appear alongside the likes of Susie Dent and Colin Murray for three weeks. On his first show, the trio will be joined in Dictionary Corner by Sir Stephen Fry. Over the course of his three weeks on the show, other guests will include Jenny Powell and Vick Hope.

Rachel moved to insist viewers are in good hands with her replacement, labelling him a "brilliant mathematician and a lovely guy". Tom meanwhile added to Metro: "All of my work online is about sharing my love of maths with the world whilst trying to make it accessible for everyone. Countdown has been doing that for a generation, so it really is a dream come true to be joining this iconic show to cover Rachel. I may even have to get another tattoo to commemorate the event."

According to his official website the lecturer at Cambridge's Robinson College has 15 tattoos which are maths-themes. Among them include one of his YouTube handle, which he has inked on his forearm.

Rachel has appeared on the show since 2009. Prior to that, the show was the home for Carol Vorderman, whose role it was to manage the letters board and check contestants' calculations to sometimes tricky maths equations. Carol held the role for 26 years between 1982 and 2008.

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