A Hollesley Bay prisoner convicted of sexually assaulting a woman while on unsupervised day release already had a previous sex offence conviction, it has emerged.

John Smith committed the latest offence on a female patient at Ipswich Hospital after he had been dropped off by prison staff for ongoing cancer treatment.

Although it was not brought up during his four-day trial at Ipswich Crown Court last week it is understood the 50-year-old was convicted of a serious sexual assault in 1992.

Smith had denied sexually assaulting the woman at Ipswich Hospital on December 14, 2014, but was found guilty by a jury.

He is now due to be sentenced at a date to be fixed.

At the time of the offence Smith had been placed in the open prison near Woodbridge as he was coming towards the end of a prison term he had received for wounding.

As a result of the incident Smith, who has also been convicted of theft, was sent back to a secure prison.

He carried out the assault while waiting to be picked up by prison staff outside the hospital after receiving his treatment.

Smith was taken to hospital by prison van and after his appointment asked a receptionist to contact the prison to get him a lift back, said prosecutor Jane Oldfield, during his trial.

While Smith was waiting to be picked up he sexually assaulted a woman patient who had gone outside for a cigarette.

Smith sat down next to the woman, who was wearing a hospital gown, and after a brief conversation he started making sexual comments and touched her leg.

The woman pushed his hand away and tried to stand up but Smith allegedly held on to her dressing gown and put his hand up her hospital gown and touched her thigh.

The woman returned to her ward where she told a nurse what had happened.

Shortly afterwards Smith went to the ward and told staff he was a friend of the woman’s mother and had come to visit her.

He was asked to leave the ward by a doctor and a nurse who were aware of what happened and police were called.

After his arrest Smith claimed it was a case of mistaken identity.

Giving evidence his victim said Smith told her: “When I have sex with you, you will like it.”

The woman said when she pushed Smith away and told him not to touch her he smiled and laughed at her.

Following Smith’s conviction a Prison Service spokeswoman said: “We welcome the conviction of this offender and our thoughts are with the victim in this case.

“Open prisons are used to test offenders in the community before their eventual release. They are fully risk-assessed before this takes place and in the vast majority of cases, prisoners comply fully with the conditions they have been set and are returned to custody without issue.

“In the rare incidents where these terms are breached or a crime has been committed, offenders will be returned to closed a more secure prison and reported to the police for investigation, as happened in this case.”