The Brit winning star launched her Prismatic World Tour in Belfast, on May 7th and this week she'll perform to thousands of fans across four nights, at the iconic London arena.

Katy told me "Four nights is Hugeness! Because I only did one show the last time I was here, so I'm thrilled to be able to come back and play it a few more times as I love London. I feel very adopted here. There are so many shops and little gorgeous things I get to pick up along the way here. I always squeeze in a bit of shop! I love Libertys, Harrods and Selfridges..and I have high tea and baked beans for breakfast and Sunday roasts. I just go all out!"

The 107 date world tour will tour the UK, Australia and America between now and December. Speaking to me earlier this year, Katy told me "the last show was almost like a broadway production , which is cool but now I have more room to express myself.. I love that I'm kicking it off in the UK as it raises the bar for me, so I'm really excited. The stage is like nothing I've ever done..I get to be up close and personal to all my fans. And of course I'll be flying around the arena with other fun things, I'm going to bring all the bells and whistles but it won't be so highly narrated as the last one was.."

So what's the message for any fans going to see the show? " You know I think they're going to have a real musical experience, with stunning visuals and they'll get close to me than they could ever. And there's some spontaneous moments which are fun and I get to pick some people out of the audience at random. No they don't work for me! And I think you'll be able to say that you'll hear all the songs you love.."

Hear Katy talking to me, earlier this year, about the world tour and more. And note that I was also invited onto the stage to sing Legendary Lovers.

I'll hold you to that Katy.