An obsessive husband was jailed for a minimum of 30 years yesterday for the murder of the stepsister of the Carphone Warehouse tycoon David Ross and her lover.

Alex Marshall, 37, was convicted of stabbing to death his estranged wife, Fiona Marshall, and Richard Flippance at a bungalow owned by Mr Ross. He was also found guilty of arson, having set fire to the property in an attempt to hide the attack, on April 2 last year.

Mrs Marshall, 41, and Mr Flippance, 44, were spending their first night together in the bungalow on the Manor Farm estate at Brampton Ash, Northamptonshire, when the attack took place.

Passing sentence at Birmingham Crown Court, Mrs Justice Rafferty said that Marshall could not bear to see his wife happy and had planned a murder that effectively left their son without a parent.

“Richard Flippance was a decent man who had done you no harm. Your son, a motherless child, is now effectively fatherless,” she said. “Four lives — Fiona’s, Richard’s, an eight-year-old child’s and yours — lie all blighted as a result of your actions and those of three decent living families,” she said.

Mrs Marshall had met Mr Flippance, a designer from Thame, Oxfordshire, through an internet dating agency about a month before their deaths, the court was told.

In the weeks before the murders, Marshall, who worked as a security guard at a Tesco supermarket, was “spying” on his estranged wife. He gained access to her e-mail and internet dating account in an attempt to discover the identify of her new boyfriend, the court was told.

Mrs Marshall died of eight stab wounds, and Mr Flippance was stabbed three times. The jury was told that DNA from Mr Flippance was found in the footwell of Marshall’s car.

They also heard that Marshall was discovered with singed hair and eyebrows and had a burn mark on the tip of his nose when examined by police after his arrest. Marshall claimed that a gas cooker had blown up in his face. Witnesses-told the court that the bungalow was engulfed in flames at about 2.40am.

The Marshalls met while working together in London, and married in 1997. A year later, Mrs Marshall gave birth to their son.

They moved into the bungalow at Manor Farm in 2002 but their marriage broke down in 2005. Mr Marshall went to live with his father in Rushden, Northamptonshire, while his wife and son stayed at the bungalow. During this time, police and Mrs Marshall’s solicitors wrote a number of letters to her husband, warning him about his conduct.

Friends said that Marshall was critical and aggressive towards his wife and that she had been visiting a counselling centre for victims of domestic abuse.

Marshall had denied two charges of murder and one of arson. He was given two life sentences for the murders and six years for arson.

He will serve a minimum of 30 years.

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