Two L. glaucoides put in a brief appearance this afternoon from 14:35-14:45. One or the other (or possibly even a different bird) was there briefly at 14:15 or so, this bird was last seen gaining height and disappearing off, wings looked very white but not really sure as not photographed and not seen that well through binoculars.
Photos of the other two birds below to add to the discussion on the GRC blog. Having looked at the photos I would say today’s L_glaucoides b appears to be the one referred to as Kumlien’s No 2 in the blog. The other bird photographed today appears to have pale outer primaries although as I only managed 2 grabbed shots as most of the gulls took off before I had a chance to find the second bird on the ground and only picked it up as it flew past so the light and focus isn’t great.
P.S. also Red Kite high over heading west just before these two turned up.
L_glaucoides a1
L_glaucoides a2
L_glaucoides b1
L_glaucoides b2
L_glaucoides b3
Glamorgan Bird Club 
Nice photos Peter. The top two photos (a1 & a2) shows a gull with a much more Iceland Gull look to it to me. In particular the unmarked outer primaries – the primaries looking paler as you work out from P1 to P10 which is more typical of Iceland. I was wondering for a while whether the appearance was a trick of the light but the heavily worn areas in the greater coverts show this is a different bird to the lighter of the 2 Kumlien’s Gulls that has been present. It would be nice to see a spread out upper wing shot, but it looks fairly good for Iceland Gull to me.
I agree that the lower three photos (b1, b2, & b3) looks like Kumlien’s No2 as you have suggested.
I wonder how many white-winger there are in the Fendrod area?