Yes, a moulting adult - an unfamiliar plumage to most (including me). I remarked on Twitter yesterday that it seemed odd that it should have moulted quite so much this early on in the 'autumn', which made things all the trickier for Simon when he found it. He got the species ID spot-on though, and alerted people quickly. First Somerset one since the famous juvenile on Meare Heath in 2006, found by the late Alan Bundy.
I think it might be a male given the pattern of the remnants of summer plumage, but in some ways it would be more likely to be a female heading south (and moulting) this early. Most males will still be involved in the last stages of parenting duties, though it could be a failed breeder of course.
