Prince William will feature in gay lifestyle magazine Attitude.

Prince William

Prince William

The 33-year-old heir to the throne revealed on Tuesday (14.06.16) he will be the first member of the royal family to appear in a gay magazine and will use the interview to rally against bullying of lesbian, gay, bisexual and transgender (LGBT) youths.

The Duke of Cambridge was at the US embassy in central London to sign a book of condolence for victims of the gay nightclub shooting in Orlando on Tuesday - where 49 people died and dozens were injured by a lone gunman - and spoke to Craig Petty, the president of LGBT association Glifaa, and told him he would be appearing in the magazine.

Craig said: "I told him what I do and he said he's going to be in Attitude magazine. I was really nervous about meeting the royal couple, but they are both great at putting you at ease.

"I think it's great that they have come here today to show their support."

Celebrities who have appeared on the cover of Altitude, which comes out today (15.06.16) include Gary Barlow, Daniel Radcliffe and Liam Payne.

The news was kept tightly under wraps but Attitude managing director Mike Buckley recently teased "exciting announcements" would be made.

He said: "We will have some exciting announcements to share soon."

The Prince has campaigned for LGBT rights and to quash bullying in schools.

In the book of condolences, as his wife stood solemnly by his side, he penned: "With our deepest condolences and with our thoughts and prayers to all those affected."