Yeah, I've just been checking out yar68's 'Bastard Heron's Border Horse' Flodden-themed thread - they look very nice and use the Essex 15s with 'steel bonnets' and lances, which is pretty classic.
Essex do have a Border Lancer and and Mounted Arqubusier in a morion that look pretty good, and I'm not totally wedded to 10mm, that just seemed the most convenient. I shall think on gents, thanks for all your replies, and if anyone else has any suggestions I'll happily take them. But at the mo, the front runners are probably the Pendraken ECW chaps, with a possibility of supplementing them with some Miniature Figurines 12mms if they scale OK.