The comic actor Chris Langham was under suicide watch in jail last night after being convicted of downloading child pornography.

The award-winning actor and writer had claimed that he accessed the images of horrific sexual abuse while researching paedophilia for the BBC television series Help.

But a jury at Maidstone Crown Court took less than three hours yesterday to find him guilty of 15 counts of making an indecent photograph. Each offence carries a maximum sentence of ten years in jail.

The Bafta-winning star of the BBC political drama The Thick of It was cleared of having sex with an underage girl, who claimed that he took her virginity when she was aged 14.

Langham, 58, sat with his head bowed as the jury returned its verdict and looked close to tears when he was refused bail and remanded in custody until he is sentenced on September 14.

He blew kisses to his three sons as he was led to the cells. They blew kisses in return but remained calm.

Langham, who is divorced from his older sons’ mother and has remarried, has not been allowed to see his two younger children, aged 9 and 11, on his own since being charged.

He had admitted in court viewing adult pornography, but denied being attracted to children.

Police raided Langham’s home in Cranbrook, Kent, in November 2005 as part of Operation Ore, an investigation into paedophiles paying to access child pornography on American websites. Forensic science experts found more than a dozen video clips of girls as young as seven being sexually abused, raped and tortured on three computers.

The clips, which ranged in duration from three seconds to nearly six minutes, had been created between September and November 2005.

During a police interview the actor produced a written statement in which he said that he had downloaded the images while researching the character for Help. He claimed that the show was to feature a sex pest called Pedro whose catchphrase was: “I’m only a minor offender.”

However, his co-writer, the comedian Paul Whitehouse, told the court that he knew nothing about such a character and said that there would be no need for Langham to look at child pornography as part of his research.

Langham had sobbed in the witness box while claiming that he had been sexually abused as a child and wanted to look at the pictures as a way of coming to terms with what had happened to him. Judge Philip Statman said that there was no defence in law to downloading child pornography for the purposes of research or because he had been abused as a child.

After his arrest, a woman Langham had known as a teenager contacted police claiming that she had been abused by him from the age of 14. The girl was starstruck and besotted after seeing Langham in Les Misérables in the West End. The woman, now 25, and her mother, who also testified for the prosecution, attended the musical more than 50 times and became on such good terms with the actors that they were allowed to wander around backstage. The jury heard stories of luxury hotels, dinners at the Ivy restaurant and expensive gifts. Langham admitted having sex with the girl when she was 18, but denied that anything happened before.

The woman, who cannot be named for legal reasons, was portrayed by the prosecution as sweet, naive, immature and impressionable. She was described by the defence, however, as a liar and an attention-seeking fantasist. She had a history of making allegations of sexual abuse and of relationships with older men, the court was told during the three-week trial. Langham’s lawyers said that she had made false gang rape accusations against schoolmates, saw the actor as a father figure and was trying to destroy him through spite because he was no longer interested in her. The jury cleared him of six counts of indecent assault and two charges of serious sexual assault.

David Whitehouse, QC, pleaded for bail to be granted, saying that Judge Statman could impose a suspended sentence next month. The judge responded that the custody threshold had been passed because the images were level five, the most serious category of child pornography. The judge told Langham: “In my judgment, and I’ve thought long and hard about this, it would be a misplaced kindness to give you bail at this stage.”

Detective Inspector Derek Cuff, of Kent Police, said: “Let’s not forget that child abuse images circulating on the internet are real situations involving real children who are sexually abused for others’ gain and gratification.”

Diana Sutton, of the NSPCC, said: “There is no excuse for downloading images of children being raped. Chris Langham committed a serious offence that contributed to the suffering and degradation of those children.”

The jury’s deliberations were delayed by nearly four hours when a juror overslept and had to be woken by the police. After the juror did not turn up for the 9.45am start, his whereabouts were checked with hospitals. A security scare at the bus station failed to explain the delay: he usually took the train. Police then asked to see closed-circuit television footage from his station. Officers knocked at his door every 30 minutes, to no avail – and the judge then ordered that the door be forced to check that he had not collapsed. At 12.30pm the juror was found asleep. There was no evidence he had been drinking. He was taken by police car to Maidstone Crown Court.

After commending and discharging the jury, Judge Philip Statham kept the juror behind and told him that what he had done “on the face of it constitutes a very, very serious contempt of this court”, but that he had otherwise “behaved well. On balance – just – I’m not going to take this matter any further.” The man had written to apologise, the judge acknowledged.

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