Adam Lambert - Mercurial gift of an American Idol

Reality TV graduate Adam Lambert is slipping into Freddie Mercury's leotard again. The first openly gay US No 1 artist tells Luke Blackall about singing with Queen

You’re my best friend: Adam Lambert on stage with Queen guitarist Brian May (EPA)

It's hard to place Adam Lambert. A runner up on American Idol in 2009, his first album had a strong hint of glam rock, his latest stuff has a strong flavour of pop and emo, and he looks like a young (and slightly more handsome) Gary Numan. To top it all off, he's gay. While a gay pop star in 2012 might not sound so unusual in the UK, in the US it is.

And this year Lambert achieved a remarkable feat as his second album, Trespassing, was the first record by an openly gay male solo artist to top the US Billboard album chart. It may sound implausible, but the other homosexual stars, such as Elton John and George Michael, were not "out" when they hit the top of the charts.

But the stir caused in 2010 when Ricky Martin chose to reveal his sexuality or when, earlier this month, Frank Ocean, a member of hip hop outfit Odd Future, blogged about having had a relationship with a man, shows that the US is still some way behind much of the rest of the West when it comes to openness about homosexuality.

Lambert is not only surprised at being the first, he is also surprised at the fuss, having been out since his late teens. "I think for a long time the music industry has been scared of it, of out artists, it's been more of a niche thing," he says. "But music doesn't have an orientation, a good song is a good song, so if you're getting hung up on the artist's sexuality in your enjoyment of the song, then maybe you need to examine your own comfort level a little bit."

One of his new tracks is "Outlaws of Love", about being ostracised for falling in love with the "wrong" person, and comes, he says, at a time when change is coming to attitudes in America.

"We're in the midst of this big civil rights movement," he says. "It's beautiful to see how people are powering through and I think the timing of that and my notoriety is a privilege. I feel I do have a certain amount of responsibility – because I have a visibility that not a lot of people have in the gay community, especially in the music industry – to be comfortable, to be open." The other curiously straight creative industry in the US is Hollywood, with whose members Lambert, perhaps surprisingly, has more sympathy.

"I can understand that with actors, they want to get cast in different projects and so they have to be believable as this, that, or the other, in order to pull someone in emotionally," he says. "I get that. I get why certain actors want to stay in the closet. But with music, it's a little more autobiographical."

Is there not a suggestion that an actor coming out couldn't be good for the industry and the community?

"I've thought about it a lot and I can see why an actor coming out is a bold move, and it's very supportive of the community and visibility, and challenging stereotypes are big parts of our movement, but unfortunately they may be sacrificing certain work they can get. And what's more important? They are probably looking out for themselves first."

The 30-year-old seems to have a lot more (of value) to say than the average reality-show-anointed pop star. He also points out that his recording process is more comprehensive than many of his peers. He worked on Trespassing for a year and a half, recording more than 50 songs in the process. The ones that did make it onto the final record were played with until he felt satisfied.

"I'm my own worst critic. I nitpick details. And I know that I put every song through the wringer."

While he won't be drawn on comparisons to contemporary artists, he has a seemingly endless list of 1990s stars who influenced his latest work, from Missy Elliot to Gwen Stefani to 2 Unlimited. The album progresses from a positive first half to a darker second, and explores his life post-Idol, from the dark, exhausted days after a world-tour to the realisation that he is "a lucky motherfucker".

Despite this, he admits his relatively new arrival to fame wasn't quite the stream of parties, freebies and non-stop glamour that he had anticipated.

"I was wrong! I didn't get invited to any fabulous parties, not really," he says. "I thought it was going to be the free pass to some exclusive club. In actuality, it creates a lot more obstacles, socially.

His first major introduction to the appetite of the celebrity press came last year when he was involved in a fight with his Finnish boyfriend Sauli Koskinen in a bar in Finland. Today Lambert blames it on a combination of jet-lag, lack of sunlight and just too much to drink. And despite some reports, he says that he wasn't technically arrested, just taken to a police station "to sleep it off".

"The next day, we were like, 'what just happened?'" he says, still looking slightly embarrassed. "It was a very childish, silly, stupid thing." Today he and Koskinen are happy and have been dating for more than 18 months, even though he admits to having "arrested development when it comes to relationships".

The release of his latest work coincides with one of his biggest opportunities yet, touring with Queen. He performed with Roger Taylor and Brian May when they were guests on American Idol, and he then performed as frontman at this year's MTV European Music Awards and, this week was in Freddie Mercury's role again for three dates in London.

With their high ranges and power, Lambert and Mercury have some vocal similarities, even though their personalities (Lambert's openness and Mercury's shyness) and routes to fame seem quite different.

"I can't sing [the songs] as well as Freddie Mercury, of course I can't, he wrote them," he says. "I don't want to mimic him, that would be disrespectful to his memory. My goal is to be myself, but to make sure that I'm singing the songs as they were intended and [ask] 'what was the intention emotionally and musically here?'"

One thing that they do appear to have in common is that, just like Mercury helped break down boundaries in the UK in the 1980s and 1990s, Lambert's success could well help do the same thing on the other side of the Atlantic.

Adam Lambert's album 'Trespassing', and its first single, 'Never Close Our Eyes', are both out now