Chris Tarrant has spent over a week in hospital after suffering a mini stroke at Heathrow Airport following an 11-hour flight.
The Who Wants To Be A Millionaire star apparently started feeling unwell on his Thai Airways flight home from Bangkok.
He then collapsed while picking up his luggage at Terminal 3, and was rushed to Charing Cross Hospital on Saturday 1 March.
Doctors first thought he'd suffered an asthma attack, but then found a potentially fatal blood clot in his leg.
According to the Independent, doctors performed emergency surgery to destroy it before it dislodged and caused a full stroke.
His agent and manager, Paul Vaughan, told The Sun: "The doctor describes it as a mini stroke, probably brought on by the asthma and bronchitis on the plane. They found a clot which they managed to break up.
"It was a clot in the leg and that can immediately go to the brain or lungs."
The TV presenter had reportedly been filming a second series of Chris Tarrant: Extreme Railways, and had been in the Andes and Burma before heading back to the UK via Bankgkok.
Mr Vaughan said Tarrant is made of 'stern stuff', but said: "He is determined to leave hospital. But he's not going back to work. This is a nasty wake-up call."
Chris Tarrant rushed to hospital after collapsing at Heathrow Airport
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