She was not ticking the boxes that the record companies wanted and that is a problem that we have. We miss artists. We miss the most amazing talent that's out there, and Eva Cassidy was one such talent. She wasn't going to tick the boxes, but actually ultimately she really does. The people spoke, the people bought her albums.

To me, a great singer - it's not a sport - so it's not about just being good technically. It has to move you, it has to leave you going "I've got goosebumps". I've not really bothered to listen to Eva Cassidy from a technical point of view, because I've never had to. I've just enjoyed her music and thought "Gosh, she just touches the soul". But because of the documentary I then studied her voice and technically she is like a master of her craft.

[on Eva Cassidy] I think there's a vulnerability and a nakedness to her music. I think that for some people, because she's died, there is that thing of "It's a bit too close, I can't listen to that vulnerability". But for me, she is probably one of the greatest singers that this world has known.