black woodpecker sighting?

Earlier this morning I was cycling through Ashton Court in Bristol, and heard a woodpecker noise.  I looked over and in a tree hollow there was a medium-sized bird, which looked entirely black, that looked back at me and then turned around to carry on tapping at the tree with its beak.

I've had a look online and this appears to be a black woodpecker, which is unusual for the UK..?  Should I be reporting this anywhere?