By Dominic Casciani
Home affairs reporter, BBC News
Parts of the trial of a man accused of murdering an 86-year-old author are to be held in secret on national security grounds.
Allan Chappelow died from head injuries
A judge at the Old Bailey ordered some details to be withheld from the public, saying prosecutors had "compellingly" made their case for the secrecy.
Allan Chappelow was tortured before being killed and left under copies of his own George Bernard Shaw biography.
Counsel for Wang Yam, 45, who denies the charge, opposed the secrecy order.
Mr Chappelow, who wrote a number of works about Bernard Shaw, was also the author of Russian Holiday - an account, published in 1955, of his experiences in the Soviet Union after he became one of the first Britons to be allowed to travel there.
The wealthy recluse lived alone in a large but dilapidated home in the affluent Hampstead area of north London.
Police launched a murder investigation after the author's body was found in June 2006 after lying undiscovered for about a month. They believe that thousands of pounds was stolen from his bank account.
Mr Yam, was later arrested in Switzerland and extradited to the UK to face trial for murder and related allegations of deception.
'Very difficult decision'
During a special two-day hearing, prosecutors made an unusual request for parts of Mr Yam's trial to be held in camera, excluding the press and the public on the grounds of a risk to national security and the need to protect the identity of a witness.
They said the risk was related to material in the defence case, and that a minister had signed a special Public Interest Immunity certificate relating to part of the case.
Anonymity orders or screens are regular features of sensitive trials - but orders to go in camera are very unusual in criminal proceedings.
Mark Ellison QC, for the Crown, told the court on Monday that there was a strong possibility that if the order was not granted, then the prosecution might not proceed.
Counsel for Mr Yam opposed the application, along with seven media organisations including the BBC.
But in his ruling, Mr Justice Ousley allowed the order, saying that private legal argument had convinced him of the need for secrecy.
He said the Crown had made a "sound case" that there was a serious risk of the prosecution not proceeding without parts of the trial being heard in private.
"The discontinuance of a murder prosecution would be a very serious matter," said the judge.
"The protected interests at stake make a prosecution decision [not to proceed] a very real possibility - although it would be a very difficult decision."
In his ruling, Mr Justice Ousley said that he rejected arguments aired by the defence in private that the prosecution's application was "forensic blackmail".
"If the defendant could not rely on his defence, then that would mean that the trial would inevitably be unfair," he said.
"I'm quite satisfied that the defendant can have a fair trial with the order the Crown seek. The issues raised [in private hearings] cannot be dealt with by lesser measures such as anonymity or screens. There could be a real risk that the trial would not proceed.
"The press and public will be excluded from the court for parts of the hearing."