The Masked Singer's Mushroom drove the judges wild with her performance of Gnarls Barkley's Crazy.
Ross said: "I think you're a professional singer but none of the clues I could make sense of - education, teaching and nature. I think it might be Lily Allen."
But McCall thought the education clues had helped her guess Mushroom's identity.
She said: "It helped me a bit - she is a TV presenter, she' a mathematician and she is crazy, I know her - she is Carol Vorderman. I've never heard Carol Vorderman sing, so..."
Ross interrupted: "I heard a sing once!" implying Vorderman was not as strong singer.
Gilligan said: "I don't know how I found the clues to this but think it's pop singer Katie B. I think she lives out in the country now."
And Ora guessed Mushroom was former Girls Aloud star Kimberley Walsh.
— The Masked Singer UK (@MaskedSingerUK) January 22, 2022
But many viewers believe they have guessed the true identity of Mushroom, and that she is in fact former Voice Of An Angel Charlotte Church.
The Welsh singer once released a pop hit called Crazy Chick, and now runs a woodland school in Wales where she teaches her three children.
Christopher Reilly tweeted: "Charlotte Church is mushroom. She has just started a nature retreat #MaskedSingerUK"
Lisa Mansell commented: "Mushroom is Charlotte Church crazy chick!! #TheMaskedSinger."
And LouGuerin said: "Mushroom is Charlotte Church , she runs an education facility in the forest #TheMaskedSinger."
Shayna tweeted: "Mushroom -Charlotte Church (had a single called crazy chick) and lives on a farm - so one with nature #TheMaskedSinger."
Traffic Cone performed Take That's Back For Good on week five of the mystery celebrity singing contest and also dropped a clue about candy.
Comedian Gilligan said: "You mentioned candy. Someone who has the title Candy in their song who is a very funny person - it could be Robbie Williams."
But his fellow judges weren't convinced with Davina McCall saying she believed Traffic Cone was somebody older who has a background in musical theatre - guessing Michael Ball.
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