Len Goodman hid his cancer battle from his Dancing With The Stars colleagues, according to reports.
The much-loved dancer, who died aged 78 on Saturday, had been working on the US version of Strictly up until November last year.
Len had been on the show for 17 years, however the "perfect professional" is said to have kept his health worries to himself.
A source said: "The news about Len caught many of the production team by surprise. There was an enormous feeling of sadness and grief because Len had brought so much fun and joy to the show, as well as being a perfect professional.
"Last Fall, Len was certainly less of a presence around and while he looked thin, that frailty was just thought of as him getting older.
"Obviously, now the suggestion is that he was dealing with something very aggressive and keeping it to himself," reports The U.S. Sun.
The source added that Len was a ""consummate professional" up until his last show, telling bosses he didn't want to do a farewell dance as he preferred to "shuffle around these days".
In a tragic foretelling, Len predicted his own death just six months before his passing was confirmed by his family.
Len would have turned 79 on Tuesday, but in an interview in 2022, the star revealed he expected to die in 2023 because his dad passed away suddenly when he was 79.
"My dad had the right idea, he loved gardening and he had a stroke while he was out in the garden. He was 79 so if I go the way of my dad, that'll be next year," Len told the MailOnline.
"I don't make a fuss about stuff like that. It's like when you have a car — you keep it serviced but even so, you'll have some trouble with your carburettor and you'll need to get it fixed, and eventually the whole thing will conk out, and there you go.
"It's more about the journey, and mine has been lovely."
Following the news of Len's death, tributes poured in for the seasoned star.
Prime Minister Rishi Sunak and the Queen Consort said they were saddened by the news.
Meanwhile, Strictly's Craig Revel Horwood said he was in mourning for his friend, tweeting: "I’ve just woken up to the sad news that my gorgeous colleague and dear friend Len Goodman has passed away.
"My heart and love go out to his lovely Sue and family. Len Goody Goodman is what I always called him and “It’s a ten from Len & seveeeeern”will live with me forever. RIP Len."