Baroness Thatcher has been taken to hospital with an infection after suffering a bout of flu.
The 85-year-old former prime minister has been admitted to Kensington's Cromwell Hospital for "routine" tests and treatment.
She is expected to leave hospital within the next few days.
Last week, the former Tory leader had to pull out of a birthday party in her honour at Downing Street after reportedly falling ill with the flu.
She is understood not to have fully recovered, and this week aides called in a doctor to assess her condition before she was taken to hospital.
On Tuesday night, her son Sir Mark arrived to visit Mrs Thatcher - prime minister from 1979 to 1990.
He said: "She's been recovering quite well but the doctors wanted to bring her into hospital for some routine tests over the next couple of days.
"If they go according to plan she'll be home shortly."
Sir Mark said his mother was "in good spirits" adding that her admission was "entirely precautionary".
Photo: ę Rex