A young thug whose criminal record was described by a magistrate as “one of the worst” he had seen laughed yesterday after he pleaded guilty to indecently assaulting a 92-year-old woman on a bus.

Police have applied for a rare two-year prohibited behaviour order to be placed on Damien Stewart Thorne after he attacked the woman in front of horrified onlookers in Palmyra on March 18.

The woman had just thanked her driver and was trying to get off the bus on Canning Highway about 3pm when Thorne reached down and assaulted her while using obscene language.

He abused the driver when he was asked why he got on the bus without paying and hurled profanities at a young couple who were sitting near the back.

Thorne’s actions were captured on CCTV and were witnessed by a number of passengers.

The 28-year-old, who appeared in Fremantle Magistrate’s Court by video link from prison, laughed and smiled after pleading guilty to indecent assault and disorderly conduct. When magistrate Richard Huston asked him what he found so amusing, he said: “I don’t know mate.”

Mr Huston described the sex attack as appalling and said it was concerning for the victim and the whole community. He said that Thorne’s criminal record was one of the worst he had seen.

Thorne was subject to two suspended imprisonment orders at the time for two counts of assaulting a public officer.

He had been sentenced to eight months jail, suspended for 10 months, for each of the charges.

Mr Huston said it was likely Thorne would have to serve the suspended jail terms and would get extra time for his “horrifying” crimes on the bus.

Police prosecutors told the court that they wanted Thorne to be issued with a prohibited behaviour order but did not indicate what the terms would be. The orders allow serial antisocial criminals to be named and shamed on a government website and banned from activities related to their crimes.

Thorne represented himself yesterday but Mr Huston suggested he speak to a lawyer before his sentencing.