A sex beast who preyed on young deaf boys is back in jail after an observant cop caught him with indecent photographs of children.

But a judge was powerless to extend the predatory paedophile’s stay behind bars beyond May 2012, despite hearing of a “serious history” of child abuse.

Graham Gilford, 49, was caught with 168 sick pictures of children hidden in his Croydon home and at a secure storage unit, Croydon Crown Court heard on Friday.

The photographs were discovered by an eagle-eyed police officer who spotted a card for a secure storage unit in Imperial Way in Gilford’s wallet.

He was immediately sent back to prison after it was discovered he was out on licence for a previous jail conviction of making indecent images of children in 2008.

Judge Stephen Waller said he did not have the power to give Gilford, an ex-special police constable, a sentence starting after May 2012 – when Gilford is expected to be released for the previous offence.

He sentenced him to 16 months in jail to run concurrently.

In 1991 Gilford was jailed for preying on 13 boys in his care at Oak Lodge, a deaf school in Wandsworth, over a seven-year period.

Gilford was caught with the secret stash of photographs soon after he moved to Croydon from Bromley in June this year.

The 49-year-old, who was attending a help group for sex offenders in Croydon, was visited by a police officer from Jigsaw, a special unit managing registered sex offenders.

The observant copper noticed the sex beast had a mobile phone with a camera and internet connection, which he was not allowed under the terms of a previous conviction in 2008.

Gilford was taken to Croydon police station for questioning, where the policeman spotted the card for the storage unit.

A search of the lock-up in Imperial Way uncovered 32 photographs of children being abused. Police then searched Gilford’s home and discovered three memory cards for a camera with more than 100 indecent photographs on them.

Gilford said the pictures dated back to 2007 and that he had been caught with them before, but claimed he had forgotten to throw them away.

Gilford was immediately sent back to prison for violating the conditions of the sentence imposed on him for making indecent images of children in 2008, at Southwark Crown Court.

Judge Waller said: “You are 49 and have a serious record. In 1991 at the central criminal court you were sentenced to a substantial time for indecent assault on young males.

“In May 2008 you were sentenced to 12 months in prison on an extended licence for 16 counts of making indecent images of children.”

He also ordered Gilford to give up his mobile phone and the photographs of children.

Graham Gilford started preying on young boys 28 years ago.

The ex-special police constable joined Oak Lodge School for deaf boys as a handyman and impressed those in charge by learning sign language.

He was soon promoted to house parent, responsible for looking after vulnerable children. From this position of trust he was able to groom and sexually abuse victims as young as 10.

The boys he abused were too frightened to report the abuse that occurred between 1982 and 1989 but a brave group got together and reported their traumatic experiences to the headteacher.

One victim, aged 12, told the Central Criminal Court through a sign language interpreter: “I just could not stop him. I was small and frightened. He told me what to do and I obeyed. It was a school. I thought that was what I had to do. I did not know better.”