A VIOLENT sex attacker who tried to rape a terrified mother after lying in wait overnight in her garage has had his prison sentence slashed by top judges.

Dangerous Derek Johnston was jailed for 11 years following the assault which left the Southampton housewife fearing she would be killed as her children played upstairs.

When she managed to escape, the 40-year-old fled to the roof of her house, sparking a 14-hour stand-off with police as he threatened to hurl himself off.

Now Johnston, of Ridding Close, Shirley, has successfully had his sentence reduced by 18 months, after London’s Appeal Court ruled his 11-year term was “somewhat too long”.

He was convicted of attempted rape and three counts of assault by penetration at Southampton Crown Court in March, following the ordeal in July 2013.

The court heard how he pounced on the mum while she used the washing machine in her garage, where he had been waiting for several hours.

Prosecutors told how he pinned her to the ground and began to take off his jeans as he prepared to rape her.

In a video recording played to the court, the woman said: “I thought he was going to kill me.

“I could hear my children running around upstairs and I thought I would be lying dead downstairs and no one would know.”

She described how he held his hand around her throat before trying to rape her.

It was only when the woman’s mother arrived at the front door that the victim managed to bite Johnston’s hand, cry out for help and get away.

Johnston ran upstairs to the bathroom and escaped onto the roof where he remained into the early hours.

Officers were forced to seal off surrounding streets while police negotiators on a crane desperately tried to coax him down in baking 27C heat.

As darkness fell police stood down – returning to the property in the early hours to find he had vanished.

They finally discovered him hiding in a storage cupboard under a bed in the same home the following day and sent him to the cells.

His legal team challenged both his attempted rape conviction, arguing there was not enough evidence, and the severity of his punishment, and while Lord Justice Elias, sitting with Mrs Justice Cox and Mr Justice Simon, rejected his conviction appeal, they agreed to cut his sentence.

But Lord Justice Elias ruled: “There was plainly material which could properly be left to the jury.

“We see nothing wrong with the judge’s ruling and, accordingly, reject his appeal against conviction.”

However, the judge went on to rule that Johnston’s 11-year sentence was “somewhat too long”.

Although the rape bid was violent and terrifying for the victim, it was not “seriously sustained”, he said.