Former Mastermind presenter and author Magnus Magnusson has been diagnosed with cancer.
Magnusson presented Mastermind for 25 years
He has cancelled a number of public appearances, including a talk at the Cheltenham Literature Festival to mark his 77th birthday.
A statement from the family said the presenter was undergoing tests, but was "in good fettle".
He fronted Mastermind for 25 years and has recently been promoting his new book Fakers, Forgers and Phoneys.
The Festival's co-ordinator Christin Stein said "It is of course very disappointing that he cannot be here, especially as he was also going to be one of the judges in an educational event.
"We are very sorry for the audience who will not have a chance to see him after all."
His daughter, Sally, is also a TV presenter but the family said they had no further comment at the moment.