John Alford, the actor who appeared in TV series including London’s Burning and Grange Hill, has been found guilty of sexually assaulting girls aged 14 and 15.

The 53-year-old, who was tried under his real name, John Shannon, was charged with four counts of sexual activity with the younger girl and charges of sexual assault and assault by penetration relating to the second teenager at a property in Hertfordshire on 9 April 2022.

At St Albans crown court on Friday, a jury convicted Alford of all charges after a week-long trial and more than 13 hours of deliberations.

Alford, of Holloway, north London, put his head in his hand and shouted “wrong, I didn’t do this” from the dock as the verdicts were read out in court.

Jurors heard during the trial that Alford sexually assaulted the girls while they were drunk after a night out at the pub. All of the offences took place at the home of a third girl whose father was friends with Alford.

The former actor, who played Billy Ray in the ITV drama London’s Burning and Robbie Wright in the BBC children’s series Grange Hill, bought £250 worth of food, alcohol and cigarettes from a nearby petrol station in the early hours of the morning, including a bottle of vodka, which the victims subsequently drank.

Alford then had sexual intercourse with the 14-year-old girl in the garden of the home and later in a downstairs toilet, and inappropriately touched the 15-year-old girl as she lay half asleep on the living room sofa.

During the trial, jurors heard that, after being arrested, Alford told Hertfordshire police officers: “This stinks. This is a setup.”

Alford told jurors of his previous convictions, which go back to 1999. They included convictions for the supply of drugs, disorderly behaviour, drink-driving, causing criminal damage and obstructing police. He claimed the conviction for the supply of drugs led to him being “blacklisted” as an actor.

He said during the trial that he had “never touched either of them girls” and sobbed while giving evidence, telling jurors: “I haven’t done this. No DNA. I didn’t touch them. I think science proves me not guilty.”

The 15-year-old girl Alford assaulted said: “We were all just like dozing off. That was when John started to touch me.” She said she felt “absolutely sick” after the assault.

She said she immediately showered after being dropped off at the house of the other girl Alford assaulted, where the girls went into the bathroom together and “spoke about everything that happened”.

She spoke out about the incidents while visiting a different friend’s home on 11 April. “I had a mental breakdown to my best mate’s mum in the garden and she called my mum,” she said.

In a video of her police interview played to the court, the 14-year-old girl said she had never had sex before the night of the alleged incidents. “I told him to stop because I didn’t want to have sex with an old man,” she said.

Recorder Caroline Overton granted Alford conditional bail before his sentencing at the same court on 4 December.

She warned the defendant he had been convicted of “very serious matters” and should expect to receive a custodial sentence.

• Information and support for anyone affected by rape or sexual abuse issues is available from the following organisations. In the UK, Rape Crisis offers support on 0808 500 2222 in England and Wales, 0808 801 0302 in Scotland, or 0800 0246 991 in Northern Ireland. In the US, Rainn offers support on 800-656-4673. In Australia, support is available at 1800Respect (1800 737 732). Other international helplines can be found at ibiblio.org/rcip/internl.html