Sir Ian McKellen blames a lack of phone sex on losing an ex-boyfriend.

The 75-year-old actor believes youngsters nowadays are missing out on interacting with people because of their obsession with technology, but thinks he would've been able to hold onto one of his lovers if he'd engaged in raunchy conversations over the telephone when he was away from home starring on Broadway.

Ian - who came out as homosexual in 1988 - said: ''I'd been on Broadway for a year communicating with my boyfriend in London, through letters.

''When I got back I couldn't be surprised that he'd decided not to live with me anymore.

''But if we'd had the internet, if we'd had Skype, phone sex, it would've probably been different.''

The 'Hobbit: The Battle of the Five Armies' actor - who first starred on Broadway in 1967 before returning for two plays in the 1980s and again this year - also joked he is an ''expert in the missionary position'' because he's played so many heterosexual lovers, but wouldn't have a problem orgasming on stage with a man.

While being interviewed by his 'Hobbit' co-star Martin Freeman for Shortlist magazine, he added: ''I did 'Bent' [a play about the persecution of homosexuals in Nazi Germany] on stage. My character and the other leading character have sex without touching, actually.

''I wouldn't have a problem orgasming on stage while talking to another man. People say that's brave. To me it seems quite nice.

''When I did 'Scandal', my first film after coming out, my character, John Profumo, was a raging heterosexual.

''I said to Edward Petherbridge, 'My first scene's with Joanna Whalley and we've got to make love.' So he drew this little diagram.

''I've still got it. I was 50! I'm an expert in the missionary position.''