Hmm, still looks really pale overall and the creamy fringes to the coverts rather broad plus the alula contrastingly dark. Only overexposure in harsh light? Because on the other hand e.g. the pp is maybe too long for an Issy? I find it's an interesting bird...
Other opinions would be welcome!
I think you're right Roland, this bird is well worth a 2nd and a 3rd look. That black alula!! The photo is slightly overexposed but that would affect the alula as well, not increasing the constrast. It's starting to look very good to me. A pitty that there are no more photos, but these might just do it if well "squeezed" for info.
I agree structually it doesn't seem right for Isabelline (too small head) but even if taking overexposure into account, the plumage looks really good IMO. However, probably the photos are not good enough to really nail it. Pitty...
In any case, the following reference is relevant in this context (sorry, I don't have a pdf, only the magazine):
From the Rarities Committee's files: Identification of autumn Isabelline Wheathears. British Birds 93, vol. 10: 488-492.
Thanks for all the pics, Dave. I'm afraid they don't help much. Just now I found time to have a look at my desktop computer. Hope you don't mind, I altered one of the pics. Indeed, it looks like a Northern to me now, though a pale one. The wings are just too long (almost reaching the tail tip)... sorry for the fuss.
To all contributors to this post, very many thanks for your opinions and reasoning behind those opinions. No need to apologise for the fuss, your comments have been very much appreciated. Thank you to one and all. All the best, Dave.