Fire crews were called after a small fire started at the Duchess of York's house in Surrey.
The Duchess of York was not at home at the time of the blaze
Firefighters tackled the blaze in a bathroom at Dolphin House in Englefield Green, Surrey, on Tuesday.
A spokeswoman for Surrey Fire Service said: "We were called to Dolphin House at 12.43pm yesterday, where there was a small fire in the bathroom."
Sarah Ferguson, 48, was not in the house at the time. Her housekeeper is thought to have raised the alarm.
Fire crews said the blaze was extinguished at about 1330 GMT and no-one was injured.
The extent of the damage is not known.