Confidence: It's likely to be this, but I can't be certain.
Notes: I am going with Northern Eggar because the pale central band is broader and 'fades' out more gradually towards the trailing edge of the forewing than in images of Oak eggar I have seen. Also because I am 'reliably' informed that in my locality I am unlikely to find Oak eggar. I do not insist that I am correct and welcome any comments or thoughts to the contrary. Male insect.