Tredegar House

A white lady has been seen in the house and grounds; she is thought to be Gwyneth Erica Morgan, the sister of the 2nd Viscount of Tredegar. She walked out of her London abode one night and her body was found in the Thames months later. When her father died, her remains were allowed to be interred with the rest of her relatives.

Update 30/8/21: The Facebook page for this property informed me, "We continue to hear stories from people who have reported experiences that they believe have been abnormal, however in an old house there are a number of factors that may create unexpected events. I hope this helps." In further correspondence, I was told, "While we don't keep an official record of reported incidents, some people believe they have heard voices or seen figures in the house, and they've said these incidents have happened to them within the past 18 months."