Carrie Johnson, the wife of the former prime minister Boris Johnson, has said there could be “up to 1,000, if not more”, victims of the black-cab rapist, John Worboys.

Johnson, who helped bring the serial sex attacker to justice, said she had been contacted by more women who believed they had been assaulted by him.

Worboys is serving a life sentence after drugging women in his taxi by offering them spiked drinks after pretending he had won money. Last week the Parole Board said he “continues to represent a high risk of committing further serious sexual offences against women”.

Johnson, one of several women who spoke out to keep Worboys behind bars, said news that he had been refused parole came as a “huge relief” to many survivors.

She told Good Morning Britain: “The truth is that his crimes span from, what we know, from 2000 up to when he was convicted in 2009. And he was a cab driver for that duration, out potentially every night in his cab, so there could be up to 1,000, if not more than that.”

She said more people had come forward saying they believed they had been in his cab after watching an ITV dramatisation of the case. This “might really help keep him behind bars for good”, she added.

“I think there’ll be women who, like me, were drugged, who might not realise they were drugged, who just thought: ‘God, maybe that last drink didn’t sit well with me.’ Or now maybe they’ve seen what’s happened and they think: ‘Oh well, it’s done.’ I would urge them to come forward if they can,” she said.

Worboys was first convicted in 2009 of 19 sexual offences linked to attacks on 12 women between October 2006 and February 2008. He was given an indefinite sentence for public protection with a minimum term of eight years.

In 2019 he was sentenced to life with a minimum term of six years after more victims came forward about crimes he admitted to, which took place between 2000 and 2008.

Johnson was a 19-year-old university student when she met Worboys in 2007 after a night out in Chelsea as she waited for a night bus to her mother’s house in south-west London. He offered to take her there for £5.

In his cab, he offered her a celebratory glass of champagne, saying he had won a lot of money at a casino. “Thankfully though – and my goodness, I am thankful – I didn’t drink it,” she wrote in the Daily Mail of her experience. “As we continued chatting, I slowly poured the champagne, bit by bit, on to the carpeted floor of the taxi so he wouldn’t notice.”

She recalled that he pulled up near Putney Common, which was dark and deserted, and got out, she believes, waiting for the drugged champagne to take effect. Then he returned with a bottle of vodka, got in the back seat and, despite her protestations, insisted she take “a quick shot”.

He dropped her off after she told him her mother was waiting for her and, crucially, he gave her his phone number should she ever be stuck for a lift again, she wrote.

After making it home, she said, she “never made it into my bed”. “Instead, I passed out in the bathroom, lying in the empty bathtub, fully clothed,” she wrote.

She came forward as allegations against Worboys emerged and said she was able to identify him in a lineup and provided the police with the phone number he had given her. The publicity around the case led to further victims coming forward.

Worboys will be due to be considered for parole again in about two years’ time.