The reason why the Redpoll spp on 9th May was not sub-specifically identified at the time is that the wing length was outside the range in Svensson for male Mealy Redpoll ('Flammea') and at the very bottom of the range for female Mealy Redpoll (and therefore much too short for 'Rostrata' - North Western Redpoll). Apologies for not putting that in the original post but I did not have the information to hand.
It might not be clear from the photos in the original post that the bird contains red markings on the face and breast - although nothing like one would expect from a male Mealy (the male Mealy on 9th May was an adult and this bird is a first year).
The reason the bird was photographed at the time was because of its unusual appearance. Whilst it shares a number of features with Lesser Redpoll (three of which were caught at the same time) - including wing length, brownish upperparts, some buff underparts etc. It also shares some features with Mealy - 'appearing' large, having white wing bars, grey streaking on upperparts, white vent, grey around the face, pale greyish rump (with some pink). And other features with North Western - large bill, straight (if not convex) looking culmen, brownish upperparts, white wing bars, buff on underparts, heavy streaking on buff background on flanks - lacking extensive pink on breast associated with male Mealys.
An interesting bird nevertheless which went down as an unusual Lesser Redpoll at the time ...
Maybe this spring we will get some more interesting redpolls - which adds a new dimension to birding on Hilbre - prior to 2008 there was only one previously documented record of Mealy Redpoll on Hilbre; during 2008 we had three!