The producer worked with the pop star on the track 'Alien' for her forthcoming new album, 'Britney Jean', and is now such a big fan he's planning to see her perform at her residency in Las Vegas, which starts in December.
He told NME magazine: ''I've done one song for the new album, called 'Alien', which is really good. I'll be in Vegas, seeing the show. I've become a huge fan of hers, actually. I always liked her, but when I started to dig into her repertoire - and there's masses of it - I became a superfan, really. You'll find me in the audience singing along.''
He said: ''Oh don't start me on Blur. Put it this way, I'm not going to work with them again - Damon was really awful. That's all I'll say. Let's put it this way, I wouldn't care to go back. I wouldn't be hurrying back to do that album. I didn't get paid! But, you know, I'm not the first.''
William previously had a good relationship with Blur, producing songs on their albums '13' and 'Think Tank'. He has previously also been behind huge hits by Madonna and All Saints.
Perry performed 'Rise' and 'Roar' before Clinton accepted the nomination to be the Democrats' presidential candidate.
Bruce Springsteen will release rare tracks from 1966 in new album 'Chapter and Verse', which will accompany his autobiography 'Born To Run'.
There's still no reunion planned though.
Not broadcast in its entirety since 1967, a full restoration will be played in select cinemas to support Ron Howard's 'Eight Days a Week' touring...