LONDON (AFP) ― Britain’s former prime minister Margaret Thatcher was in hospital Saturday recovering from a minor operation to remove a growth in her bladder and may remain there over Christmas, friends said.

The 87-year-old “Iron Lady,” Britain’s first and only female premier, was doing “absolutely fine” having been admitted to hospital on Thursday feeling unwell, her spokesman said.

But the operation has raised fresh fears for the health of Britain’s conservative prime minister from 1979 to 1990, who has been a subdued figure in recent years and a far cry from the fiery figure of her heyday.

Current Prime Minister David Cameron, who like Thatcher leads the Conservative Party, wished his predecessor “a speedy recovery,” his 10 Downing Street office said.

Thatcher ― the 20th century’s longest continuous occupant of Downing Street ― has suffered a series of minor strokes and in 2002 was told by doctors to quit public speaking.

With dementia taking hold, she has appeared increasingly rarely in public.

Her daughter Carol once revealed that she had to be repeatedly reminded that her husband Denis had died in 2003.

Public relations executive Lord Tim Bell, Thatcher’s adviser for her three general election victories, said she had undergone “minimally invasive” surgery.

“She felt unwell earlier in the week. She went to the doctor. The doctor sent her to the hospital,” he told BBC television.

“The hospital examined her, discovered a small growth in her bladder and they decided to remove it using what they describe as minimally invasive surgery, so no heavy anaesthetics and so on.

”The operation was a complete success, her condition is satisfactory.

She’ll stay in hospital for a few more days to recuperate and then she’ll go home.

Thatcher’s daughter has been at her side in hospital. Her son Mark is believed to be outside Britain on holiday.

Asked how long she might remain in hospital, Bell said: “A few days is the phrase being used. “It’s perfectly possible she’ll be there across Christmas.”