What was your first festival experience?
Oliver’s mum took us to Reading when we were 14, which, when I think about it now, is pretty hilarious. She was a massive fan of the White Stripes. She saw that Oliver and I were falling in love with live music and took us along. She was way more hardcore than us: she stayed down at the front through punk bands like Dropkick Murphys to watch the White Stripes. I remember being amazed by it all, but at the same time thinking: Get me away from this place.

You’ve gone from the mid-afternoon siesta slot to headliners in a short time. How does it compare?
It’s been quite sudden but although it’s more pressure being high on the bill, our band is better suited to night. We’re awful in daylight – there’s a lot of bumping around and I feel so exposed. We put on a much better show in the dark. I feel more comfortable surrounded by lights and the smoke.

You’re quite shy. Do you find the intensity of festivals hard?
You can try and hide, but actually I find it more relaxing to watch the other bands on the stage I’m about to play on. It makes me feel calmer than sitting backstage thinking: Oh my god, what am I about to do?

Who is your ultimate festival act?
One band who are always incredible to watch at festivals are the Kills. It’s not like they’ve got loads of stage production, it’s just them on stage, going for it. Seeing the two of them side by side, boy and girl, with no obvious lead singer – it inspired the xx hugely. Alison Mosshart came to watch us recently and I could see her from the stage with her new tequila sunrise hair. That was quite a big moment for me.

You’ve just come back from Coachella. What are the differences between UK and US festivals?
I feel like it’s normal to see English people going crazy, but in the US it’s a different kind of wild. There was a lot of screaming at a show we played in America recently and that wouldn’t happen in England. I came off stage thinking: What band were they watching? It shocked me, it was a proper One Direction scream!

How do you manage to reconcile rain ponchos and wellies with your all-black band uniform?
You’ve got to wear wellies. It would be a mudfest without them. Oliver and I went to Glastonbury in 2011 just for fun – the weather wasn’t good, so we bought wellies and got involved like everyone else. If it was raining, I think I’d wear a poncho. I would be happier if it was a black one, though.

You’re curating your own Night + Day festival this summer. As it’s your party, can you sit back and relax for once?
Oh, not at all. It’s our party down to every little detail. We’re considering everything from the atmosphere to the kind of food we want to the DJs we get to play. I’ll be well prepared for my wedding after this •

Interview by Harriet Gibsone for The Guardian