I thought at first that this was a Lesser Spotted Woodpecker but it seems more likely to be an immature Great Spotted Woodpecker. The immature birds have a red crown which disappears as it matures.
So this is one of this Spring's brood! See the link fron the RSPB, below.
http://www.rspb.org.uk/wildlife/birdguide/name/l/lesserspottedwoodpecker/index.aspx