A “predatory” former head-boy who lured a 12-year-old he met through a Merton church group into showing her underwear on a webcam has been sentenced to 40-hours' community service.

Phillip Grout, 19, of Taunton Close in Sutton, was found guilty at Kingston Crown Court last month of causing a girl under the age of 13 to engage in a sexual act.

The court heard how Grout, a former pupil of Richard Challoner School in New Malden, sent a string of indecent and explicit text messages to the girl, including one seen by her mother which read: “Do you know what happens to a man’s willy when he gets excited?”

The Loughborough University geography student, sentenced at the Old Bailey on Tuesday, also engaged in several hour-long webcam and MSN conversations with the girl, who cannot be named for legal reasons.

Between November 2008 and January 2009 he indulged in inappropriate conversations, asking questions about her school uniform and pyjamas, and on one occasion persuaded her to show him her bra.

Grout, a volunteer at the church group and a fundraiser for several African charities, deleted text messages to the girl from his phone and wiped his computer shortly before he was interviewed by police, the court heard during his one-week trial.

But copies of records taken from her phone and computer were read to the court by prosecution lawyer Guy Ladenburg.

He said: “Why were you asking a 12-year-old in webcam conversations what clothes she was wearing?”

Grout replied: “There was nothing sinister to it, it was all just a joke. In hindsight it looks very silly.”

Mr Ladenburg said: “It looks more than silly Mr Grout. In my view, it looks predatory.”

In another charged exchange, Mr Ladenburg asked why he had engaged in conversations about a children’s movie.

He said: “Do you think the film Sponge Bob Square Pants was made with an audience of first year university students in mind?

“I’m suggesting this was a pattern of behaviour where you tried to manoeuvre her to exactly where you wanted.”

Grout wept as character witnesses described him as a caring, capable and honourable role model.

Family friend and IT manager Charles Jeffery said: “He’s a really well-respected and nice young man. I’ve never seen him do anything wrong.”

The jury found him not guilty on a second count of causing a girl under the age of 13 to engage in a sexual act.