After spending time in London, Monte Carlo, Paris and New York in the 1970s, he settled in part of the family seat, Ickworth House in Suffolk, becoming the 7th Marquess in 1985.

He struggled with addiction to cocaine and other drugs, serving several jail sentences for possession, and was known for his flamboyant lifestyle and homosexuality.

His brief marriage in the mid-1980s did not last because of this, and he became increasingly depressed as he lost money and faced bankruptcy, culminating in the sale of the remainder of Ickworth House to the National Trust.

He died in early 1999 of complications resulting from his drug addiction, and was succeeded by his half-brother, Frederick Hervey, 8th Marquess of Bristol.

[5][6] The 6th Marquess, who had been jailed for jewel theft in his youth, behaved harshly towards his eldest son, according to friends of the family.

"[3] His mother remarried giving him Teddy Lambton, a Newmarket racehorse trainer, for a stepfather,[1] and then a half-brother, George, who became a Conservative councillor.

John Hervey did not get on well with Yvonne, whom he referred to as "Miss Crimplene",[9] and he reportedly hurled a glass at the wall when he received a telegram from his father announcing the marriage.

[3] Around this time, his father attempted to prove that John was an illegitimate child, so could not inherit his titles and estates, but was unsuccessful.

[10] Along with his half-brother Nicholas, Earl Jermyn attempted to sue his father's estate after Yvonne and her children were named the principal beneficiaries in the 6th Marquess's will, but failed.

[4] He modelled himself on Oscar Wilde[3] and began to use drugs and alcohol; the Oxford Dictionary of National Biography designates him a "wastrel".

[3] He eventually acquired a personal fortune worth up to £35 million,[12] including oil wells in Louisiana and a 57,000-acre (23,000 ha) sheep farm in Australia.

[9] In his early 20s, he lived in a small flat and sold second-hand Bentley cars; friends recall he was at his happiest during this time.

[3] On another, while accompanying his secretary Angela Barry, he crash-landed the helicopter in a field, and walked to the nearest farmhouse, demanding to use the phone while leaving mud everywhere.

[13] He became known for his dark sense of humour; on one occasion he allowed a young woman to ride a rubber dinghy into the middle of the lake at Ickworth and then shot at it with an air rifle, sinking it.

[3] According to the Marquess, his father and mother both suffered from manic depression (now known as bipolar disorder) and he felt the same, though he appreciated that years of cocaine abuse had not helped matters.

[20] The National Trust were unimpressed with the Marquess' behaviour, including dangerous driving around the estate and lack of control over his wolfhounds.

[7] By the early 1990s, friends were concerned about the Marquess's addiction to drugs, particularly since multiple prison sentences had done nothing to alleviate it.

[26] His half-sister Victoria shared similar sentiments, and stated that she has avoided drugs as a result of her relationship with John.