A cousin of Winston Churchill has died, leaving the son he once described as a "black sheep" to inherit one of Britain's most prestigious aristocratic titles.

The Duke of Marlborough, who owned the opulent Blenheim Palace estate which is worth an estimated STG100 million (A$182.5 million), died "peacefully" in his sleep at the age of 88.

His death prompted tributes, with Prime Minister David Cameron describing him as a "good man and friend" - but it also paves the way for his once-troubled eldest surviving son to inherit his title, and potentially his estate.

Jamie Blandford, 58, currently known as the Marquess of Blandford, will now become the 12th Duke of Marlborough, a Blenheim Palace spokesman said.

Advertisement

But he declined to comment on whether the Marquess will now also inherit the palace and its lucrative estate.

The Marquess has waged a long and very public battle with heroin and cocaine, often splashed across the front pages of the newspapers.

Dubbed by some as "the wayward peer", he spent STG20,000 in just four months to pay for his drug binges.

He spent several spells in prison, mainly for driving offences, and was in and out of court throughout the late 1980s and 1990s.

His turbulent lifestyle led to his estrangement from his father, who branded him a "black sheep", and he was all but disinherited from the family fortune.

But after years of drug addiction and clashes with the law, the Marquess is now a reformed character.

He has been drug-free for several years and moved back to Blenheim Palace following a rapprochement with his father.

The palace in Oxfordshire was built in the early 18th century in the opulent baroque style. Boasting 187 rooms, it dwarfs both Buckingham Palace and Windsor Castle.

- AAP