Fred Barrras was killed after breaking into Bleak House

Martin, 55, was found guilty at Norwich Crown Court of murdering 16-year-old Fred Barras, by a majority verdict of 10 to two.

The jury also found him guilty of wounding with intent Mr Barras' accomplice Brendan Fearon.

Martin, described in court as eccentric in the extreme, was cleared unanimously of attempting to murder Mr Fearon and of possessing a firearm with intent at his farmhouse called Bleak House in Emneth Hungate, near Emneth, Norfolk.

Martin had denied murdering 16-year-old Fred Barras on 20 August, saying he was a victim of crime and was acting in self-defence.

'Reasonable force'

Mr Makin added that he had been flooded with messages of support for Martin, and papers for appeal would be lodged by next week.

The case has sparked a debate about the level of force which is acceptable in tackling burglars.

Jailing Martin, Mr Justice Owen told him householders could use reasonable force to defend themselves from burglary.

After the trial ended, Det Chief Insp Martin Wright, said: "Burglary is without doubt one of the most despicable crimes there is but I would stress to everybody it is up to the police to resolve it and this very tragic case when there has been no winners shows that is the case."

But Martin's actions in tackling the burglars were given support after the verdict by chocolate heir Sir Peter Cadbury, who told the BBC it was legitimate for a householder to use force against an intruder "if the householder himself feels threatened".

Brendan Fearon: Shot like "a rat in a trap"

He told BBC Two's Newsnight programme on Wednesday: "A lot of my friends sleep with loaded guns under their beds and I don't think they can be criticised for doing that, because if they ring the police, it will be 35 to 40 minutes before a car gets there.

"I have had a loaded gun by my bed for the last 40 years, but in July last year, when a burglar took every piece of jewellery my wife had and my wallet and a lot else, he took the gun too."

He added that he had now armed himself with a crossbow instead, and said he would not hestitate to use it if a burglar broke in late at night.

Victims of Crime Trust director Norman Brennan said the verdict was "yet another example of how the criminal justice system can make criminals out of victims of crime".

'More resources'

The level of burglaries in the area where Tony Martin lived is also expected to prompt the Norfolk police force to ask for more resources in the wake of the case.

In the part of west Norfolk around his farm, the level of burglaries reported to the police was almost double that in surrounding rural areas.

BBC correspondent Peter Hunt says the force will be lobbying government to get extra cash, after accepting the public perception is that policing levels are totally inadequate.