wahey, I have had a reply from Liz who compiled the list on thechildballads.com.

she says "I'm glad you like our Child Ballad site, and I hope it will be of use to your group. The research was done mostly by me and Claire Huang (FolkPhile). Sandy Paton sent us a list of the CBs from the recordings in his catalogue, and I got some of the rarer ones from Sandy's friend John Mazza. I asked John if he wanted to be credited on the website, but he never responded.
Claire and I are not professionals in any capacity, either as musicians or otherwise, just amateur enthusiasts. So if anyone spots mistakes on the website, please let us know.
Certainly we are interested in additions to the list. I will add your group collectively as a contributor under 'Mudcat' if that's ok."

I have asked if she minds if I put her email address on here but shan't do so until she gives me the ok, until then if you want it then PM me. I've also suggested she might like to join Mudcat herself as it sounds like she'd not come across it, so we'll see what happens...