Prince William made a surprise appearance on the Graham Norton Show, which airs tonight on BBC One. Here’s what we learnt...

Related: King Charles heaps praise on Prince William after bombshell Prince Harry interview

William spoke with Graham Norton and his fellow guests about the origins of the Earthshot Prize, and its role in identifying and supporting innovators around the world.

The Prince of Wales said: “For many years I was hearing stories about environment issues and one thing that struck me was the negativity and doom which got me down. I thought we could do something more powerful and more optimistic and the idea of an awards' ceremony came about and we could talk about urgency and optimism together.”

The future monarch revealed his family’s love of The Celebrity Traitors, adding that he even touched paranoid faithful Ross Kemp “to see what reaction I got from him”.

When asked how he switches off, William said: “It is music and film.…