THE sister of the murdered playwright Joe Orton believes a former lover of her brother could hold the key to the killing and has appealed to the man to come forward.

She is also hopeful that pages from her brother’s diaries can still be found – and that they could explain why he was killed.

Leonie Orton, the playwright's 72-year-old younger sister, spoke exclusively ahead of the fiftieth anniversary of the death of her brother, who was killed by his lover Kenneth Halliwell in their flat in Islington in London.

At the time, Orton had been hailed as the greatest new talent in the British theatre – with plays like Loot and Entertaining Mr Sloane – but on August 9, 1967, he was beaten to death with a hammer by Halliwell, who then committed suicide by overdosing with sleeping tablets.

Leonie Orton, who is appearing at the Edinburgh Book Festival later this month, believes that the missing pages cover the last few days of her brother’s life and that they could explain exactly why Halliwell snapped when he did. One theory is that Orton may have been preparing to leave Halliwell for another man.

In an interview in today's Sunday Herald Life Magazine she said she was in no doubt that there are pages missing from the diaries.

She said: “I’ve been through the diaries and I’ve counted the days when Joe didn’t write anything and he never missed more than a day, a day and a half. There’s pages missing – sure as birds can fly there are missing pages.”

Orton believes the missing pages may contain information about some of her brother’s famous friends (at the time of his death, he was writing a script for Brian Epstein and the Beatles) or perhaps a new lover – and that when Halliwell read them, he erupted.

Orton believes that at some point before the killing, Halliwell may have ripped out the relevant pages and destroyed them, but she also thinks it is possible that her brother’s agent, the late Peggy Ramsay, may have removed the pages, perhaps to protect a famous person who was mentioned or the identity of a man that Joe was seeing.

Simon Callow, the actor and a close friend of Ramsay, told the Sunday Herald that Orton’s theory was possible. He said that Ramsay could have tampered with the diary. “She was perfectly capable of it, she was capable of almost anything in defence of her clients.”

Orton also believes there is still a chance that a lover of Joe’s who may have been mentioned in the diaries is still alive and that he could explain what was happening in the final days of her brother’s life. She says she is hopeful that the man, who would be in his 80s at least if he is still alive, may hear of her appeal for information.

Leonie Orton is at the Bosco Theatre, George Street, Edinburgh at 2.30pm on Tuesday August 22.