Lord Tim Bell, the leading PR and advertising figure who was a close adviser to Baroness Thatcher, said she was expected to need several days of recuperation. It could mean she will spend Christmas in hospital, where she has been accompanied by her daughter Carol.
Lord Bell said the former politician had been in some pain earlier in the week and was sent by her doctor to hospital where it was decided the operation was required.
It was a short procedure using what was described as "minimally invasive surgery", he said."She's fine," he added.
More top news
Barnsley's promotion winning football team will be welcomed back this afternoon with an open top bus parade followed by a civic reception.
Millwall fans who caused problems at the match against Barnsley could face lifetime bans, the club said.
The mother of a 13-year-old from Lincolnshire is launching a campaign to raise money for an operation to correct her twisted spine.