Always a pleasure to see one of the woodpeckers, especially at close quarters. They're usually spotted (geddit?) in flight, with their characteristic flight pattern of a few wing beats, then stop with wings closed for a second before beating the wings a few more times and closing them again, and repeat, giving them an undulating flight path.
This chap has become something of a regular on the suet nibbles feeder. A lady friend occasionally pops by but I've no idea if they're together.
You can tell it's a male great spotted woodpecker, Dendrocopos major, because of the red patch at the back of the head / nape of the neck which the female lacks. Unlike their diminutive cousin, the lesser spotted woodpecker (which used to be Dendrocopos minor but which has recently been relocated and is now known as Picoides minor), the greater spotted are doing well.
They are best known as a result of their drumming when establishing territories. Despite their striking appearance they're actually rather reclusive and difficult to see, so if you're keen to find them it's best to learn their distinctive calls and flight pattern. The drumming tends to be short, only 4 or 5 seconds long, tailing off at the end, whereas the lesser spotted drums for longer and more persistently: the opposite of what you might expect.