Robert explained that he "believed [he] was fit enough to take on Strictly and its demanding schedule" but has now realised that it was no longer possible to continue after seeking urgent consultation with his heart specialist.
His Peep Show and That Mitchell and Webb Look co-star David Mitchell is among those devastated by the news, and has revealed whether or not he'd consider replacing Robert for the competition.
Taking to Twitter, David wrote: "This is sad! They did some really brilliant dancing, I thought. Sorry there won't be more. And to those asking if I'll be stepping in to replace him: I'm afraid not. I prefer to dance like nobody's watching. And I can only do that if nobody's watching."
This is sad! They did some really brilliant dancing, I thought. Sorry there won't be more. And to those asking if I'll be stepping in to replace him: I'm afraid not. I prefer to dance like nobody's watching. And I can only do that if nobody's watching. https://t.co/VATyJhQFg5October 13, 2021
Robert's dance partner Dianne Buswell was among those who replied to David's statement, writing: "You know I would be more than happy to teach you a tango". So who knows? Maybe she could convince David to take to the dancefloor one day!
Dianne has also commented on Robert's sad departure, saying: "As a massive fan of Robert’s I was delighted to find out that he was joining the Strictly family. On top of this, to find out he was my partner was the icing on the cake.
"We made a great team, worked hard and had a good laugh along the way. I am so proud of the three amazing dances we produced. I know Robert had a lot more to give to the competition but his health, of course, comes first and I wish him a speedy recovery. I feel lucky to have danced with him and to call him a friend."
Strictly Come Dancing will continue this Saturday at 7pm on BBC1 with 12 couples taking to the Strictly Ballroom floor to impress the judges and the voting public.
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Lucy joined the WhatToWatch.com team in 2021, where she writes series guides for must-watch programmes, reviews and the latest TV news. Originally from Northumberland, she graduated from Oxford Brookes University with a degree in Film Studies and moved to London to begin a career writing about entertainment.
She is a Rotten Tomatoes approved film critic and has a huge passion for cinema. She especially loves horror, thriller and anything crime-related. Her favourite TV programmes include Inside No 9, American Horror Story, Stranger Things and Black Mirror but she is also partial to a quiz show or a bit of Say Yes to the Dress!