I sometimes take quite a while to figure out what I've photographed when I come back and examine all the shots, and this was a good case in point. It was actually in a walk-in aviary at Pensthorpe in Norfolk so if I'd had time to read the signs I'm sure my life would have been easier but I was in a rush.

I'm fairly sure it's a Ruff, which can be found in the UK (including Norfolk) but is a fairly rare migrant, stopping off here on its way from Scandinavia to Africa. I assume this is a female, but the male in breeding plumage is quite the sight to behold – Wikipedia has some good images. Another shot of the same bird below.