A farmer driven to despair by burglars is today starting a life sentence for killing a teenage intruder.

A jury yesterday found former Oxfordshire schoolboy Tony Martin, 55, guilty of murdering 16-year-old Fred Barras at Bleak House, his remote Norfolk farm.

Bachelor Martin, who attended Cokethorpe public school in Ducklington, near Witney, between 1957 and 1961, was convicted on a majority verdict of ten to two.

His legal team is to appeal.

Norwich Crown Court was told how the teenager and two other men set off from their homes in Newark with the intention of burgling Martin's home, which was derelict but contained antiques. The farmer was well-known locally for his outspoken views on criminals, according to Rosamund Horwood-Smart, prosecuting.

He had been burgled three months earlier, when the thieves took a chest of drawers, china and items of sentimental value. After that raid, Martin made dire threats about what he would do if burglars came back.

"When he reported the (May) burglary he told the operator that the burglars had left some furniture outside and they may come back, and if they did return he would blow their heads off, she told the court.

Martin had been "vitriolic about criminals especially gyipsies and talked of putting them in a field surrounded by barbed wire and machine-gunning them.

Miss Horwood-Smart said Martin lay in wait for the burglars and shot them "like rats in a trap.

Anthony Scrivener, defending, said Martin was a victim of crime who was acting in self-defence.

"Self-defence is a defence to all these charges, Mr Scrivener told the jury.

Passing sentence, Mr Justice Owen said: "He killed a man who invaded his home and is guilty of murder. But this should be a dire warning to all other burglars.''