Jay, Garrulus glandarius.
Although they are the most colourful members of the crow family, jays are actually quite difficult to see. They are shy woodland birds, rarely moving far from cover. The screaming call usually lets you know a jay is about and it is usually given when a bird is on the move, so watch for a bird flying between the trees with its distinctive flash of white on the rump. Jays are famous for their acorn feeding habits and in the autumn you may see them burying acorns for retrieving later in the winter.
Photo: © Simon Olley