A teenage girl who kicked and punched a gay man in a homophobic attack has been sentenced to seven years in prison.

Ruby Thomas, 18, of Anerley in south-east London, was convicted of manslaughter last month for the attack on 62-year-old Ian Baynham in Trafalgar Square in September 2009.

The Old Bailey heard she had drunkenly hurled homophobic abuse at Mr Baynham and his friend before an altercation.

She was said to have smiled as she “put the boot” into him and the assault was described in court as a “Clockwork Orange-style” attack.

Twenty-year-old Joel Alexander of Thornton Heath, south-east London received a six-year sentence.

He admitted punching Mr Baynham in the head and claimed he had acted to protect Thomas. He was also found guilty of manslaughter.

Mr Baynham, who had just started a job as a civil servant, died in hospital of head injuries two weeks after he was attacked.

Another teenager, 18-year-old Rachael Burke of Upper Norwood, south-east London, was found guilty of affray at an earlier hearing and was handed a two-year prison sentence.

Thomas, who attended a £12,000-a-year private school, already has a conviction for violence after assaulting a bus driver in 2007.

Following Thomas and Alexander’s convictions, Mr Baynham’s family called on the public to “take responsibility” for reporting hate crimes.

Gay rights groups said that his killers’ ages proved that plenty of work still needs to be done in schools to tackle homophobia.

Stonewall chief executive Ben Summerskill said today: “We welcome these sentences. We also welcome the extension to the sentence for Ruby Thomas recognising that this terrible killing was homophobic.

“We remain mindful that the people who committed these offences were educated in secondary schools in this country in the last five years.

“If Britain’s schools continue to fail to tackle homophobic bullying then there’s a risk we’ll continue to see this sort of incident on our streets.”