Chris Langham "groomed and systematically abused" a teenage girl over a period of three years and downloaded illegal images, a court has heard.

The comedy actor, from Golford in Kent, appeared at Maidstone Crown Court on Thursday for the first day of his trial.

He denies 10 counts of indecent assault and two counts of serious sexual assault between January 1996 and April 2000. He has also pleaded not guilty to 15 counts of making an indecent photograph of a child between September and November 2005.

Richard Barraclough QC, prosecuting, told the court Langham had explained to police that he downloaded the pictures for research for a television programme.

However, he added: “If you deliberately download these type of images, you are guilty of an offence. It is no defence to say that you are doing it for research.”

Barraclough added that Langham "has an interest in young girls" and groomed and systematically abused one child. He said the actor took a girl to hotels for sex when she was 14.

David Whitehouse QC, defending, said Langham maintained he did not have sex with her and urged the jury to keep an open mind.

He told the court the child pornography images were for "research" ahead of making BBC series Help. One episode, in which Langham play a psychiatrist, involves a paedophile.

The hearing was adjourned and continues on Monday.