If Bono left, we could carry on. If I left, we'd be screwed.

I joined a band to hit things.

Unfortunately, as far as the music is concerned, what defines relevance is whether you are on the radio or whether you are on the cover of a magazine or whether you're winning MTV awards, and so on and so forth.

Relevance is a big, big question. It's more about what's your definition of being relevant. In the music world, agism is a big issue. It's about youth and youth culture. There's no other art form that I know that requires you to be a certain age.

And if I had to spend 20 years in the band just to play that show, I think it would have been worthwhile.

We all have views on what our Irishness means to us. Two members of the band were born in England and were raised in the Protestant faith. Bono's mother was Protestant and his father was Catholic. I was brought up Catholic. U2 are a living example of the kind of unity of faith and tradition that is possible in Northern Ireland.

There's a thin line between interesting music and self-indulgence. We crossed it on the Passengers record.