Bit of a tricky position, but I'm guessing it's a Great Spotted - it's beak looks bit short though - possibly juvenile?
PS got a nice view of a green woodpecker - not help required there :)
http://www.flickr.com/photos/steve_dewey/sets/72157623533703702/ (there's birds there - and some are actually sharp!)
Yes, great spotted. Rob
It could be the camera angle that makes the beak look short.
Birding is for everyone no matter how good or bad we are at it,enjoy it while you can