A former headmaster at a Croydon secondary school had sex with a 14-year-old boy he met through a Christian youth group, a court heard.

John Coatman, now aged 75 and retired, is on trial at the Old Bailey charged with buggery and two counts of gross indecency with a youth over a 12-month period in the 1970s.

At the time, Mr Coatman was headteacher of St Andrew's Church of England High School in Croydon as well as being involved with the Christian group for boys, prosecutor Corinne Bramwell told jurors today.

She told how "rough and tumble" turned sexual when the defendant was alone with the boy, who cannot be named for legal reasons.

Although the alleged victim said he was not "entirely comfortable" with what happened, he did not report it to police until 2014, the court heard.

The catalyst was the breakdown of his marriage after his wife found out he was watching pornography and meeting adults online, as well as work problems, the court heard.

In a videoed police interview played to the court, he told how he had been bullied before joining the Christian group which gave him a "sense of a home" away from his family.

He wept as he told an officer: "It was my first sexual experience and has coloured my sense of self-worth since then."

Mr Coatman, of Leyburn Gardens, Croydon, denies the charges against him.

He was made a MBE for services to young people by the Queen in 2011.