Small Green bird ID? (1 Viewer)

Hi there, whilst out on a spontaneous walk last week I encountered a pair (male and female) of small green birds near Peterborough, Cambridgeshire and looking through all my available material I can't come up with an ID. The male (presumably) was about the size of a blue tit, and was predominantly very bright green (similar hue to a Ring-necked Parakeet!). They had a warblers type of beak, and blackish-grey legs (I think). The female was larger (Chaffinch kind of size) and was a duller shade of green with brownish markings on her back and wings.
Am relatively new to this so if it is glaringly obvious what species this is, please forgive me. But as I say, none of my books seem to have anything close, so any help would be gratefully received.

Regards Richard

Hi, there are no small green birds with a marked size difference between male and female in the UK. Can only suggest two different species, perhaps a Chiffchaff/Willow Warbler and possible another warbler such as a femaie Blackcap or a whitethroat. Or faoiling that a pair of Greenfinches!