Tom: We spent a year and a half trying to find people to be in the band. We spent time with Doug and Harry before we picked them. We decided these two were the best of the bunch.
Tell us about the video
The video was only a day shoot, but because it's half-animated, it took about three months to put that on. We saw it for the first time a couple of weeks ago.
We had to have our heads clamped to make sure we didn't move. The paint itched and it took ages to come off.
What's been your highlight?
Harry: The tour. Having a number one album and getting the record for being the youngest band to get a number one, because The Beatles previously held it. It's been a crazy year, but a really good one too.
What's the key to having a successful band?
I don't think there is any formula. As long as we are having fun and people are buying the records. The fact that we write our own stuff is quite a big advantage. You can't just put anyone together. If anyone of us wasn't in the band, it would be totally different.
Do you ever complain?
We can't because we are doing what we want to do and having an amazing time. We have got the best job in the world at the end of the day - and there's no job in the world that you don't have to prepare for and work for.
What's your advice to budding musicians?
Tom: Stick at it. Four years ago, I was doubting myself and didn't know what I wanted to do. I kept on writing songs and got better and better. You never know what's around the corner...