A teacher who wrecked a promising career by sending obscene messages to two teenage girls has been jailed for 16 months.

Joe Cornwall did not meet either of the girls, but a plea to impose a suspended sentence or community order was rejected.

The 29-year-old PE teacher stood shame-faced in the dock at Maidstone Crown Court as Judge Charles Macdonald QC told him: "In my judgement, you are a person with unresolved motivation for sexual activity.

"You appear to have some kind of compulsion to send sexually explicit messages to women while dating other women."

Cornwall, who taught at Angley School, in Cranbrook, admitted three charges of causing or inciting a child to engage in sexual activity by a person in a position of trust over a 14-month period.

Keith Yardy, prosecuting, said both girls were 16 at the time the offences started.

The first girl instigated contact by sending Cornwall a friend request on Facebook in December 2009. He at first pointed out there should not be such contact between them.

There was general chat on Facebook and in text messages and he then asked her if she wanted to meet "for fun". He made references to his private parts.

"you appear to have some kind of compulsion to send sexually explicit messages to women while dating other women…” – judge charles macdonald qc

"His messages became more explicit," said Mr Yardy. He spoke of wanting to perform a sex act on the girl and a friend at the same time.

Cornwall also sent the teenager a photo of him standing bare-chested in front of a mirror. He asked for a picture of her for his birthday.

She sent one of her wearing a low cut top and later sent him pictures of her in a bra and topless.

Cornwall, formerly of Oxford Gardens, Maidstone, texted the second girl about performing a sex act on her and said he wished he was going to bed with her. He also spoke of cuddling and kissing her.

Cornwall, now of Forewood Rise, Crowhurst, Battle, East Sussex, will have to sign the sex offenders' register for 10 years. He is now banned from working with children.

The judge said he was making a sexual offences prevent order, although, "curiously", it had not been requested by the prosecution.

The judge told Cornwall: "I accept some of the messages were of an innocent and non-sexual nature, although utterly inappropriate for a man of nearly 30 to send to females of this age."

He added: "The loss of your career is your own doing."