Comedian Katherine Ryan has revealed her shock at discovering her age in an interview on The Jonathan Ross Show. 

Ryan, who is 42 and the host of the podcast What's My Age Again? told Jonathan Ross that she did the test her guests take herself and was stunned by the results.

She says: "Brace yourself, it was hurtful. I’m 42, my biological age is 77." She turned out to be biologically older than any of her guests. "It’s almost over for me. I am taking magnesium now. I eat 30 plants a week…"

Ryan gave birth to her fourth child, daughter Holland Juliette, in October last year. She and husband Bobby Kootstra also have a son Fred and a daughter Fenna. Ryan also has an old daughter Violet, 16, from a previous relationship. 

Ryan is currently writing a new book, First Born Daughter. 

"I discovered on tou tha, a lot of people who like me happen to be first born daughters. The book is about womanhood and the messiness passed on. it’s interesting to include my daughter. She’s 16 and to get some of her perspective. It’s just a lot of me oversharing as usual. I’m writing most of it and she does 10%, which is a big ask of a 16-year-old."

The other guests on the Jonathan Ross Show this week are Alan Davies, Kristin Scott Thomas, Mawaan Rizwan and Sienna Spiro.

The Jonathan Ross Show, Saturday, April 4, 10pm, ITV1.

Picture: ITV1