Beggining to look like a light Sussex, what the seller said in the first place. I have two light Sussex chicks now at 2 weeks old, they are not developing the same way and have heavier builds.
The legs are definitely white although they look quite yellow in the photos. Delaware and lightbsussex have the same markings, but light Sussex are MUCH more common in the UK. Also the breeder keeps light Sussex.. So I'll tAke that as further confirmation!