OK, so Sherlock figured out why it was proving so tricky to identify which type of woodpecker we had. Turns out they're Barbets (White-Eared Barbets). Luckily I figured this out before handing them over to Bird Guy this morning. Their plumage was becoming less and less like anything on the woodpecker page in our bird book!
I don't feel too bad about the mistake though. Both woodpeckers and barbets belong to the Piciformes order of course, having the same characteristic zygodactyl toes. What's that you say? Not too brushed up on the piciformes order? Forgotten your facts on bird feet?
So I can either be awfully embarrased about my mistake, or feel justifiably proud of rearing them this far when I am so absolutely clueless about birds.