Great Spotted Woodpecker

On Thursday morning, as I was walking through the woods from Farnborough North to Frimley, I heard a sharp chirp sound and then a black and white woodpecker flew past me and up into a tree by the path.  It was probably a female great spotted woodpecker (Dendrocopus major) as it seemed to have no red on its head.  As I walked past it played the squirrel trick of keeping on the far side of the tree trunk, but it did poke its head around several times to keep an eye on me.