A gay sexual predator who drugged and sexually humiliated teenagers at his Rugeley home has failed to persuade top judges he did not deserve a life sentence.

Robert Osbourne, 43, was jailed for life at Stafford Crown Court in September last year after he was convicted of raping two teenagers, after they were invited to Osbourne’s home on a false pretext.

Both boys, aged 16 or 17, were sedated by Osbourne, a former hospital worker, and then sexually assaulted by two of Osbourne’s accomplices.

Osbourne was prosecuted on the basis of his “joint enterprise” involvement in the rapes after prosecutors argued he goaded his two accomplices to take sexual advantage of the unconscious youths.

One of the men who Osbourne persuaded to rape the two boys was his HIV positive “slave”, Stuart Davies, London’s Appeal Court heard, and had been “recruited” by him through an internet advert. Due to the effects of drink and drugs, neither of the boys had any recollection of the trauma they had suffered.

As well as drugging the young men, Osbourne gave an accomplice, Ian Briggs, viagra and injected Davies’s penis with a drug that produces an instant erection.

At the original trial Osbourne was branded “a highly dangerous sexual predator” by Judge Paul Glenn, who jailed him for life with a minimum term of nine years.

Sir Richard Curtis, sitting at London’s Criminal Appeal Court, with Lord Justice Dyson and Mr Justice Maddison, said the truth emerged after Mr Davies complained to Staffordshire Police about Osborne’s mistreatment of him. He said he was taken into Osbourne’s house as his slave, to perform menial tasks and to “satisfy him sexually”.

Osbourne challenged the life sentence yesterday, but Sir Richard said the ultimate penalty was entirely merited in such an “appalling case.”