Kerr admitted the attack on the nurse

William Kerr threatened Pauline Dunnery with a knife, repeatedly punched her and tore at her underwear.

A judge at the High Court in Glasgow said he had subjected his victim to a "terrifying and sustained attack".

Ms Dunnery came forward to speak about the attack as part of a campaign aimed at improving security for health service workers.

Kerr, 34, had attacked Ms Dunnery in a drugs preparation room at the hospital.

You subjected your victim to a terrifying sex attack at her place of work Temporary judge Leeona Dorrian

Ms Dunnery was in court to hear sentence passed.

Temporary judge Leeona Dorrian QC told Kerr, whose address was given as Perth Prison, there was a high risk that he would reoffend and he would serve a minimum of 10 years before being considered for parole.

The court heard Kerr had two previous High Court convictions for sex offences.

Previous convictions

In 1987, he was convicted of assault with intent to ravish and in 1998 he was sentenced to eight years for a serious sexual assault.

Kerr was on licence when he assaulted Ms Dunnery, the court was told.

Ms Dorrian told Kerr: "The incident to which you have pleaded guilty is one in which you subjected your victim to a terrifying sex attack at her place of work."

Kerr broke down in the dock as he was told two background reports concluded that he was a threat to society.

Ms Dorrian said: "These both assess you as being a high risk of reoffending in general and sexual reoffending in particular. I must be concerned for the protection of the public."

I am really pleased about the decision and that women will be safe from him Pauline Dunnery

The nurse had given up her right to anonymity to join the Unison union's staff safety campaign.

She told reporters last week how she feared Kerr would kill her.

Speaking outside the court on Thursday, Ms Dunnery said she was relieved at the sentence and now hopes to move on.

She said: "I am really pleased about the decision and that women will be safe from him.

"I don't wish him any harm in prison but I am glad he is going to be locked away for a long time."

And she added: "I can't understand why someone could do something like that. I can't hate him but I want him locked away."

On how the verdict will help her come to terms with her ordeal, she said: "I am still having a lot of flashbacks and nightmares but hopefully now I will be able to move on."