The case of AB and CD has been widely described as "Britain's first secret trial". It would be more accurately described as the latest of a number of creeping moves towards secret justice.

Less than five years ago, the entire defence case in a murder trial at the Old Bailey was held in private. Fresh developments in the case of Wang Yam, the man convicted of the murder of an elderly recluse in Hampstead, could add a new dimension to the row about judicial secrecy.

Yam was convicted in 2009 of the murder of Allan Chappelow, a photographer and author, whose battered body was found in his crumbling home in 2006. Yam, a Chinese dissident who defected to the UK via Hong Kong in 1992, was arrested after thefts from Chappelow's bank account were traced to him.

Mr Justice Ouseley, the trial judge, imposed a gagging order on the entire defence case following a request from the then home secretary, Jacqui Smith. The Guardian was among media organisations that unsuccessfully challenged the judge's decision. If the order was lifted, warned Mark Ellison QC, for the prosecution, "there is a serious possibility the crown may not proceed in this case".

In April, one of Britain's most senior legal figures entered the debate in a most unconventional way. In an article for the London Review of Books, Lord Phillips, the first president of the Supreme Court, wrote that his daily cycle ride took him past Chappelow's house. He recalled the murder and trial, adding: "Very unusually, a large part of his trial was held in camera, because apparently Wang Yam had some link with the security services, which he wished to rely on by way of defence."

Phillips noted that Yam had applied to the European court of human rights (ECHR), claiming that holding part of his trial in secret had infringed his right to a fair trial.

In February, Ouseley dismissed Yam's application to lift the gagging order so he could put his case to the ECHR. Ouseley said there were "very good reasons" for secrecy, citing "national security and the protection of the identity of a witness or other person".

Yam's lawyers have applied for a judicial review of Ouseley's decision. The fact that such a respected legal figure as Lord Phillips has introduced into the public arena a "link with the security services" is seen as shedding fresh light on the case. There is no shortage of internet speculation about the reasons for the gagging order.

Yam, grandson of one of Chairman Mao's top comrades, wrote to the Guardian last year to protest his innocence. "I believe the only way to my freedom is [to] let public ... know what is my defence and what I had done in full picture. No cover-up," he said. In light of the Guardian report, two witnesses came forward earlier this year with fresh information about the case. Part of Yam's legal argument was that because his trial had not been reported, potential witnesses had not come forward.

The allegation against Yam was that he stole Chappelow's mail and probably battered him to death after being discovered by him. Yam claimed the murder was carried out by a gang he had infiltrated. One potential witness told the Guardian: "I lived a few doors down from [Chappelow's house] back in 2006. The following February, [when Yam was already in custody] I was in our house and heard a rustling in our porch. I opened the door to find a man with a knife going through our post. He pointed the knife at me and I shut the door ... He said if I called the police he would kill them." The neighbour did call the police, who advised him to change his bank details. "It is clear to me that there was a violent person or gang operating in the street and the lack of police interest was very bizarre."

A number of spy trials were held in secret at the Old Bailey during the second world war. At the height of the Troubles in Northern Ireland, quasi-judicial trials were held in secret behind the wire at the Long Kesh internment camp outside Belfast. Special courts operated there in the early 1970s and were used to authorise the extended detention of suspects rounded up by the RUC. In many cases, special branch officers gave evidence in the absence of the defendant.

Two terrorism trials, of Salahuddin Amin in 2005 and of Rangzieb Ahmed in 2008, were partly held in secret to conceal the role of the intelligence services in Pakistan.

Baroness Helena Kennedy QC described the proposal to hear the AB and CD trial in secret as a "disgraceful departure from recognised trial standards and an affront to the rule of law". She told the Guardian: "How can we expect to have influence on standards around the world when we do this? I acted for [MI5 officer] Michael Bettaney in the 1980s. It was a case involving espionage and deep secrets of the British state yet even there only parts of the trial were held in camera."

Referring to the Chilcot inquiry into the invasion of Iraq, she added: "If you can gist Tony Blair's conversations with George Bush, why not let the public have some understanding at least of the nature of the evidence and who is involved in testifying. It raises the question as to whether this is a cover for activities of US and UK intelligence agencies which are questionable."