Gordon Topen, 22, of Fulham, south-west London, the boyfriend of the prostitute, Frances Graham, stabbed Peter Wickins 19 times in a jealous rage on 18 December last year.
Topen had thought Mr Wickins, 32, of Chelsea, south-west London, was the woman's secret lover.
Topen, who denied murder, was found guilty by majority decision of an Old Bailey jury. Judge Kenneth Richardson QC told him: 'This was a dreadful murder and your behaviour afterwards has been described as callous. No doubt drugs played their part.'
On the night of the murder Mr Wickins had attended an award ceremony in Mayfair, central London. Still in black bow tie and evening dress, he slipped away from his dinner companions and picked up Miss Graham, 33, in a side street behind the Hilton hotel.
A little later he was stabbed to death with a kitchen knife after Topen burst into the bedroom of the flat he shared with Miss Graham. The dead man was stripped of his pounds 7,000 Rolex watch, his wallet, a pair of gold cufflinks and his clothing. His mutilated body, naked except for his socks, was dumped on waste land in Shepherds Bush, west London.
At Topen's five-day Old Bailey trial, Miss Graham was the main prosecution witness. She is being kept in a safe house by police after threats by Topen. She told the court he had put a contract on her head. Police were led to the killer after tracking down Mr Wickins's watch which Topen had sold.
Mr Wickins's company, Game Ltd, had won an industry award for being 'Retailer of the Year' at the computer games award ceremony for selling Sega and Nintendo games. The Surrey-based business had 14 outlets across the country.
Miss Graham originally from Shrewsbury, Shropshire, left private school with three A-levels at the age of 18. She moved to London for a course at the London Institute of Beauty intending to become a beautician. But she began taking drugs and it soon completely took over her life. She watched a previous boyfriend die as result of heroin taking, she told the jury.
She met Topen, a convicted robber, when he was 18. Miss Graham turned to prostitution to buy the drugs the pair needed. She told the court she had slept with about 20 men for money.
Ms Graham, who gave evidence for three days, told the court that on the night of the murder she led Mr Wickins back to her flat, but her client never had a chance to have sex with her before he was killed. She and Topen wheeled the body down from their sixth-floor flat in a shopping trolley to the boot of Graham's Ford Fiesta car and dumped it.Reuse content