Image copyright EMI Image caption Queen in 1975 (clockwise from top): Brian May, John Deacon, Freddie Mercury, Roger Taylor

Bohemian Rhapsody celebrates its 40th birthday on 31 October, 2015. Guitarist Brian May recalls the song's creation, and why he'll never grow tired of hearing it.

How many songs become so ingrained in popular culture that they get their own nickname? Not many - but Bo Rap is one of them.

A sprawling, six-minute rock opera, it has been Christmas number one twice, soundtracked a pivotal scene in Wayne's World, and sold 2.44 million copies in the UK alone.

Not bad for a song the record company said would never be played on the radio.

Written by frontman Freddie Mercury, Bohemian Rhapsody was painstakingly pieced together in six studios, pushing 1970s recording technology to its limits. The song's multi-tracked 'bismillahs' and 'scaramouches' were overdubbed so often that the tapes became virtually transparent.

But the band never lost faith in the track. "We all realised it was something wonderful and we should give it our heart and soul," says Brian May.

To mark the 40th anniversary, the guitarist looked back at the writing process, the boundary-breaking music video, and the song's resurrection in Wayne's World.

Image copyright EMI Image caption Bohemian Rhapsody spent nine weeks at the top of the charts in 1975

THE BEGINNING

There was no demo. It was all in Freddie's head and on lots of little pieces of paper, which he used to make notes on. And I mean literally notes. He would put A♭, C♯, D♭ in little blocks.

So Freddie had the framework in his head and he and Roger [Taylor, drums] and John [Deacon, bass] set out each part as a backing track. Then we set about embroidering it.

RECORDING 'THAT' RIFF

The heavy bit was a great opportunity for us to be at full pelt as a rock band. But that big, heavy riff came from Freddie, not me. That was something he played with his left hand in octaves on the piano. So I had that as a guide - and that's very hard to do, because Freddie's piano playing was exceptional, although he didn't think so. In fact, he thought he was a bit of a mediocre piano player and stopped doing it later on in our career.

GETTING THE SONG PLAYED ON RADIO

We were told it was going to be a hard sell, but it ended up being easy because Kenny Everett stole the tape from a playback session we had to launch the Night At The Opera album and took it upon himself to go out and play it to death.

That made everybody else sit up. All the rest of the radio outlets thought: "Oh God, we'd better get on this quick or else we'll be left behind!"

Image caption The band were not fans of the BBC's Top Of The Pops show, and made relatively few appearances after their career took off

MAKING THE VIDEO

I know it's been called the first ever music video, but it's hard to actually define these things. I know for a fact the Beatles made 35mm films of tracks - but ours was more like a mini-movie.

It was filmed with the express purpose of giving it to Top of the Pops. For those of us who remember it, it wasn't a classy programme. Top of the Pops didn't have a good reputation amongst musicians. Nobody liked it, really.

It always seemed like a bit of a travesty. If your music had any meaning, it seemed to trickle away when you were standing on a box in a studio with lots of kids around. But you could hardly knock it because it was the way that records were sold.

Image copyright EMI Image caption The band often split the song into sections during 1975's A Night At The Opera tour

TAKING THE SONG ON TOUR

Bohemian Rhapsody probably wasn't the most difficult track [from A Night At The Opera] to perform live. If we'd tried to do Good Company, for instance, or The Prophet's Song, it would have been much harder.

So, in putting together the tour, there was no particular worry about Bohemian Rhapsody. But we thought it was kind of pointless to try to recreate that huge, multi-part operatic section with just the four of us. So the solution we came to was we would go off stage, change our frocks, and come back and crash into the heavy section.

That operatic section has very often been a light show or a video show in our concerts - and I would rather have it that way than stumble through it and do something which is nothing like the record. It just makes much more sense to me to regard it as a performance art piece.

THE FIRST TV PERFORMANCE

We played it on TV for the first time on The Old Grey Whistle Test, which screened an entire show [from London's Hammersmith Apollo] on Christmas Eve, 1975.

That was a very big deal for us. It was totally and completely live. No delay or anything. If we'd had time to think about it, we would have got really nervous, but in fact we just ploughed in and thought "aha, we're ready for this". Precocious boys.

Image copyright Rex Features Image caption Cult comedy Wayne's World featured an extended segment where Wayne Campbell (Mike Myers) and Garth Algar (Dana Carvey) sang along to Bohemian Rhapsody in their car, along with several inebriated friends

WAYNE'S WORLD

I didn't know Mike Myers [who wrote and starred in the film] but he rang me up out of the blue and said: "We've done this amazing sequence in our new film - can we have your approval? And can you get Freddie to hear it?"

So he sent me a cassette and I took it around to Freddie, who was not in a good state at that time. He was… He was confined to his bed, but I took it round and played it to him and he loved it.

Strangely enough, the humour in it was quite close to our own. Because we did that kind of thing in the car, bouncing up and down to our own tracks!

THE SONG BECOMES A HIT FOR A SECOND TIME

There's a layer of humour in Queen songs - and Mike Myers managed to find it in Bohemian Rhapsody. It made it into a different kind of classic, and propelled it to a second life in the States.

There's a huge irony there - because there was a time when we completely owned America and we would tour there every year. It seemed like we couldn't go wrong - and then we lost America for various reasons, which are now history.

Freddie had a very dark sense of humour. And he used to say: "I suppose I'll have to die before we get America back." And, in a sense, that was what happened. And it was Wayne's World - which came completely out of nowhere - that made it happen.

Image copyright Press Association Image caption Bohemian Rhapsody was a key part of Queen's career-defining set at Live Aid

BUT WHAT DOES IT ALL MEAN?

I do think Freddie enjoyed the fact there were so many interpretations of the lyrics. It's an outlandish song. I think it's beyond analysis. That's not me trying to be evasive. I just think that's why we love songs - they can do something to us that a piece of text can't.

I have my own ideas and feelings about Bohemian Rhapsody - but I hate talking about it, and I generally refuse.

THE LEGACY

I'm not sick of it. You can't complain that people want to talk about it all these years later.

I still enjoy hearing it. If it comes on the radio, I'll turn it up and listen. But no air guitar. I'm too old for air guitar now.

A DVD of Queen's 1975 show at the Hammersmith Apollo will be released on 20 November.