Balbir Matharu, 54, spotted the pair and stood in front of their getaway car. But Albert and Tommy Willett drove off in the car - dragging Mr Matharu along for 40m before running over him.

Albert, 26, and Tommy, 24, from the Clays Lane travellers' site, east London, were on Wednesday found guilty of murdering Mr Matharu at the Old Bailey. The murder convictions are believed to be the first for such an offence. Previous cases where someone has been run over during a crime have resulted in convictions for manslaughter.

As the brothers were led to the cells, Albert smirked at police officers. He said: "What are you looking at? I am alive though, innit?"

Judge Christopher Moss ordered that Tommy should serve a minimum term of 25 years and Albert 27 years.

The judge, who described the Willetts' behaviour as "callous" and "despicable", had added two years to Albert's sentence to take account of a sentence he is already serving for robbery and trying to smuggle hard drugs into prison.

Judge Moss had told the brothers: "The crime is beneath contempt. Balbir Matharu was a decent, upstanding family man whose fatal mistake was to stand up to the likes of you when you tried to steal his property.

"You are a pair of career criminals and drug addicts. You have made no contribution to society - you have taken from it."

Mr Matharu, who was married with a grown-up son and daughter, worked for the family building company near the car park where he was knocked over.

Mr Matharu's daughter Baljinder, 30, said: "My dad was a decent, honourable, hard working man who loved, looked after and did everything for his family. The people who killed my dad showed nothing for him as a human being and complete disregard to his life, our lives, and anyone who knew him. Such a level of inhumanity I cannot forgive or condone."