Hi Neil
The birds in photos 2 and 4 could possibly be Common (Mealy) Redpolls, but it would be helpful to see them side-on to try to assess the colour tones of the upperparts, flanks, wingbars, etc. Also if you have any photos of the paler birds side by side with the browner looking birds, that would also provide a useful comparison :t:
Our 'British' Lesser Redpolls tend to be quite buff and brown overall, whereas the Scandinavian Common (Mealy) Redpolls are much frostier overall, being particularly grey-brown around the face and the back of the head. Other differences include paler grey brown back with whitish streaking (or tramlines), whitish rump, cleaner whiter underparts, and larger/bulkier size compared to our Lesser Redpolls.
There have been quite a lot of Mealy Redpolls around nationally, so it's worth studying your birds more closely - I'd certainly love to see more photos :t:
Cheers
Steve