I read some where someone saying Dun is very difficult to get in the UK. Sorta like how hard it is or was to get Chocs here. So, your prolly right. Unlikely to be Dun. And the truth will come out after a few months of growing goes by.My second thought was Dun too, I hatched a lot of Platinum, Dun, Blue and Black Sumatra chicks this year and as day olds sometimes the Dun chicks and the Blue chicks looked almost identical. It wasn't until they started to feather out that I could easily tell them apart.
The only problem with that train of thought is that when you cross a Choc and a Dun bird you are supposed to get a "double dilution", turning the bird a beige color... Dun is like Blue, genetically it cannot be hidden (you can't have splits) so it always expresses itself if the gene is there.
I feel like it's very unlikely that the UK Chocolates are carrying Dun, so... I still have no idea.
Do you have any pictures of the chicks in question Jean?
By the way Jeremy, are you doing Beige?