SHE was rich, alluringly beautiful, could captivate any man’s attention and once turned her pistol on a lover.

But was Alice, Countess de Janzé, the murderer of Joss Hay, the 22nd Earl of Erroll?

Her biographer, Paul Spicer, who lives near Dorchester, argues that she was.

The unsolved killing that took place in Kenya in 1941 involved the decadent upper-class Happy Valley set, notorious for its Altitude, Aristocracy, Alcohol and Adultery.

It became the subject of a book by James Fox that was made into the 1988 film, White Mischief, starring Charles Dance and Greta Scacchi.

The womanising Earl of Erroll, who was found dead in his car with a bullet wound, had been previously married to Idina Sackville, the high priestess of Wanjohi – Happy Valley – who had shocked high society with her behaviour.

Idina was the subject of a biography herself, written by her great granddaughter, the Chancellor of the Exchequer’s wife, Frances Osborne, and published earlier this year.

At the time of his murder, the earl had begun an affair with Lady Diana Delves Broughton, the beautiful young wife of Sir Jock Delves Broughton who, in the 1920s, had been one of the owners of the Ensbury Park racecourse in Bournemouth.

He was tried for the murder and, though acquitted, is still believed by many to have pulled the trigger on that fateful night.

Others have suggested the killer could have been Lady Diana, or even MI6, for the earl had displayed far right-wing leanings.

Paul Spicer, whose flowingly compelling book, The Temptress, is about the scandalous life of the Countess de Janzé (another of the Earl’s long-term lovers), does not agree.

“I had this story inside me for a long time because Alice was a great friend of my mother’s,” said Spicer, who has lived in Dorset for 50 years but lived in Kenya in his boyhood and returned there when in his 20s.

“When my mother died she left me her diaries and a book by Frederic de Janzé which she had decoded to explain who the people referred to actually were.”

Count Frederic de Janzé had married American heiress Alice in Paris and was the father of her two daughters.

The book contains extraordinary anecdotes about the life of the countess, who left Frederic and her children to become involved with the rakish Raymund de Trafford, who then back-pedalled from marrying her when fearing his family would cut him off.

Alice reacted by shooting him in a train, then turning the gun on herself.

Both survived. Alice was tried for attempted murder but avoided going to prison.

Alice, whose pets included a lioness she rescued and a baboon, and who suffered from manic depression, eventually made her way back to Happy Valley, where the sunshine lifted her spirits.

She teamed up again with Idina and friends whose risqué dinner parties included, for example, the “sheet game” in which the males would line up behind a sheet with holes revealing their private parts which the female guests would attempt to identify.

But behind the fun and frolics were jealousies that led to the murder of the philandering earl.

“Writing the book took me a long time,” said Paul Spicer, who went to Eton, spent four years in the Coldstream Guards, worked for Shell for 21 years and eventually became deputy chairman of ‘Tiny’ Rowlands’ Lonrho.

He treats his subject with surprising sympathy.

“She was a very intriguing woman, utterly beautiful with huge grey eyes, and she had a way with which she captivated men all her life,” he said.

“She adored animals, I think even more than her own children.

“I did not know that I was going to come to any conclusion on her life but things started to fall into place and gradually I came to realise that first shooting that took place in Paris was something that she might easily repeat in life,” he said.

“If she was rejected in any way by a man she was consumed with terrible feelings and was not slow on drawing out her gun.”

She also had a great belief in what she called the Great Beyond, where people would join up again in the afterlife.

So why does Paul Spicer think the killer was Alice?

His reasons are many. They include, for example:

• She had a motive. As lover of Joss over two decades she was jealous of his affair with the much younger Diana.

• She reacted oddly on seeing the earl’s body in the mortuary and showed great interest in Sir Jock Delves Broughton’s trial.

• She was familiar with guns and had used one on a lover before.

• She had knowledge of the earl’s movements on the night he was killed.

•Wide-tyred skid marks near the murder scene could have been made by her car.

•A one-time neighbour of Alice in Happy Valley told her daughter-in-law she knew who shot Lord Erroll. And her firm belief, says Spicer, was that it was Alice.

• Most tellingly, Paul Spicer – whose next book is nearing completion –was informed by the daughter of Alice’s doctor that her mother had told her about a letter of confession that had been written by Alice before her suicide just months after the killing of Joss. It had been addressed to the police.

“There is no doubt that there was such a letter,” said the biographer, who believes that the authorities did not wish to “stir the pot again” after the unsuccessful trial of Sir Jock.

“I think the letter was sent out in a diplomatic bag and has never been seen again.”

The Temptress (Simon and Schuster £14.99) is to be published next month in America where the countess was born.

“I believe I have accumulated enough evidence to bear down on the fact that the killer could have been her,” said Paul Spicer, who is married with two grown-up children.

“I know there are other theories and will continue to be. But short of being present at the shooting, who can tell for sure?”