Chris Tarrant is recovering in hospital after suffering a mini-stroke.
His manager, Paul Vaughan, said he was taken ill on a flight to London from Bangkok in Thailand on Saturday March 1 and was taken to Charing Cross Hospital.
He said: "The doctors have confirmed he has had a mini-stroke, but he is made of stern stuff, Mr Tarrant, and hopefully he will be home by Thursday or Friday."
The 67-year-old had been filming in Asia and South America before falling ill and Mr Vaughan said he would not be going straight back to work after he is discharged.
He bowed out from Who Wants To Be A Millionaire? last month after a decade and a half in which the quiz show has become one of the most successful programmes in the world, inspiring spin-off games and Danny Boyle's hit film Slumdog Millionaire.
Tarrant first found fame hosting the ITV children's show Tiswas.