Another unidentified bird

Hi, I only saw this briefly (it flew past me) so no photos.

It was about the size of a pigeon but was more slender. It was slate grey/blue coloured and had a crest. The wings were black and white (I think) and pointed. I don't recall the beak.

I've done a search and it does look like a Hoopoe but is the wrong colour. It most resembles a Blue Jay but I am in South Devon so unlikely?

Any thoughts?