Jamie Durrant, 38, says he was branded 'Fag Boy Jim' and there was a 'homophobic attitude' within the computing giant.

Mr Durrant, of Godalming, Surrey, who earns £50,000 a year designing video games for the Xbox 360 console, is suing Microsoft at a London employment tribunal for discrimination on the grounds of sexual orientation.

He said mocking emails were sent around his workplace with headings such as 'I'm Jim and I'm Gay' and 'Me and My Favourite Men'.

He said the firm did not have policies to deal with his complaints.

Mr Durrant, who has worked for 11 years at Lionhead Studios in Guildford, bought by Microsoft two years ago, said the emails began in January last year. He has been off work for depression for seven months.