At around 12:50 yesterday I saw what I called a "rainbow cloud", but since have found out it's a circumhorizon arc.
I didn't have my camera, so took this pic with my phone. I was watching it for a good 10 minutes as I was driving to work and it was a lot better before I got there.
As I understand it, it's extremely rare in the UK, so I was chuffed to see it (even though it's nowhere as fab as the ones you can see in America - or on internet ).
All I've done on this pic is crop the bottom off
This one is a zoom
And this one is a rough "enhancement"