The Metropolitan Police were called to reports of concern for the welfare of a female resident at an address in Wandsworth, south-west London, at 9.37pm on Sunday.

Police attended with paramedics and discovered a 57-year-old woman, who was pronounced dead at the £900,000 home in Ashbury Road.

Scotland Yard said the incident was not being treated as suspicious and that a file would be prepared for the coroner.

Next of kin have been informed, but formal identification has not yet taken place.

Lord Parkinson, 84, was one of Margaret Thatcher's most loyal lieutenants, and died in January last year.

According to reports Miss Parkinson, who never married, suffered from anorexia from the age of 14, became a drug addict and a prostitute to feed her addiction, struggled to cope after losing her father to cancer.

She once said: “I so very much wanted to please my father.”

Mary was fined for possession of drugs in 1987. Standing on the court steps, she said of her father: “He used to get really angry with me because he had never known failure in his life. The pressure on me was too much, and I just cracked.”

She was said to be particularly upset in 1983 when her father was forced to resign from the Cabinet after his affair with his secretary, Sara Keays, became public. 

She was the only one of Lord Parkinson’s three daughters to comment publicly on the relationship, which resulted in the birth of Flora.

Friends say her death was being treated as a case of suicide.

You can call Samaritans free, any time, on 116 123 (this number will not appear on your phone bill), email jo@samaritans.org, or visit www.samaritans.org to find details of your nearest branch.

In the US, the National Suicide Prevention Hotline is 1-800-273-8255.

In Australia, the crisis support service Lifeline is on 13 11 14.