The serial sex attacker John Worboys has admitted drugging four more women.

The black-cab driver, who was convicted of assaults on 12 women in 2008, had a decision to release him overturned in November after a public outcry.

At the Old Bailey on Thursday, Worboys, 62, pleaded guilty to a string of further offences relating to four more women.

Appearing via video link from Wakefield prison, Worboys, wearing glasses and a light grey and green shirt, pleaded guilty to two counts of administering a stupefying or overpowering drug with intent to commit rape or indecent assault.

He also admitted two counts of administering a substance with intent to commit a sexual offence under the Sexual Offences Act.

The court heard the maximum sentence faced by Worboys was life in prison.

Mrs Justice McGowan adjourned sentencing to 2 September for a report to be prepared on his history of offending and the danger he posed.

“This is a case on which the public interest is better represented by the probation service putting forward a complete history,” she said.

Ordering the defendant to be produced in court at the next hearing, McGowan said: “This is a case where the public might expect the defendant to be sitting in the dock.”

All the women made their allegations to the police in early 2018, shortly after the Parole Board announced it had decided he was fit to leave prison after serving less than nine years of an indeterminate sentence, plus time spent on remand.

The offences he admitted on Thursday date back to between 2000 and 2008 in London. Police fear Worboys may have had as many as 100 victims but, despite at least 85 more women making complaints after his 2008 conviction, these are the first to come to court.

At an earlier hearing in the latest case, the prosecutor, Jonathan Polnay, said the first of the four victims was told by Worboys, who now goes by the name John Derek Radford, that he had won money on the horses and was celebrating. He offered her champagne to celebrate and drinking it was her last memory that evening.

“She woke up the next day naked with her clothes left in a trail on the way to her bed,” he said.

“All his previous convictions relate to a very particular, identical modus operandi: picking up women in taxis, claiming he had won money gambling … [offering] alcohol laced with a form of sedative.”

After fury from victims and MPs at the Parole Board’s decision to release him, the high court ordered the board to carry out a “fresh determination” into the case and for Worboys to remain in prison in the interim.

In the aftermath, Nick Hardwick was forced to resign as Parole Board chair. He then accused the justice secretary, David Gauke, of failing to take responsibility over an inadequate dossier provided by the Ministry of Justice.