In 2006 Mark Simpson became the first person ever to win both the BBC's young composer competition and BBC Young Musician in the same year. This Saturday, his piece sparks will open the Last Night of the Proms, one of the biggest nights in the cultural calendar. We spoke to him ahead of the big day.

How did the piece come about?
I just a got a phone call from Boosey and Hawkes asking if I wanted to accept the commission for the Last Night of the Proms – it was completely out of the blue. And of course it was a resolute 'Yes!'… It was more of a case of screaming in the street. But it was definitely a yes.

It must have been a hugely important commission for you. Did you feel any pressure to change your compositional style for the work?
Well it’s a huge deal – it’s the biggest exposure you can get in the classical music world but I didn’t really feel that pressure. I spoke to [the composer] Julian Anderson at the time, who I study with at the Guildhall School, and he said ‘You’ve just got to forget all of that and write the piece that you’ve got to write’. The commission brief was ‘an exuberant concert opener’ and I had some guidelines – it wasn’t to be too long and it was for full orchestra. So I sat down and came up with the body of the piece in short score and then spent a while consolidating the material. And then I started to doubt whether it was good enough – as you do with any piece you write, but on a scale I’d not experienced before, because I knew how many people would be listening to it.

The piece is called sparks. Tell us why you chose that title.
The idea of the piece is that there’s an energy that’s quite volatile and it’s on the brink of explosion, implosion or breaking point. When the piece gets going about a minute in it’s quite relentless and very virtuosic. I didn’t want to just smack the audience in the face from the outset, I wanted to tease them in, so once I’d done the first sketch, I went back to the drawing board and wrote a new opening that is more suggestive and anticipates the energy, as opposed as just giving it away straight away.

Have you heard any rehearsals yet?
No, the first rehearsal’s on Thursday so I actually have no idea whether it works it not! There are a few things I’m looking forward to hearing to see how they sound together. There’s a whole passage where I have three trombones singing and playing at the same time through their instruments. I’ve also been quite adventurous with the ending: I have the orchestra explode, in a way, in very high, dense textures when everyone is really just going for it. The piece stops suddenly and then is quiet again. I’ll be in the audience at the Prom on Saturday and I’m really looking forward to it.

The Last Night of the Proms is live on BBC Two on Satuday 8 September at 7.30pm, the second half is live on BBC One. It will also be available to watch for seven days on iPlayer