Manna gum,
Very interesting thread - and rather interesting timing. I was doing a bit of reading up on Norfolk Greys (a rather rare British dual purpose breed) and what was used in their make up (probably not more than an hour or two before you put up the post): a mention was made of "Dark Grey OEG", and I was wondering what on earth these looked like.
Norfolk greys have very much the same colour pattern as Dark Grey OEG - and rather distinct from Silver sussex.
Some images of them can be found here
http://www.britannicrarebreeds.co.uk/br ... lkgrey.phpThis colour pattern is actually the subject of a current discussion at The Coop - mainly in the context of distinguishing between non-melanised black (E) and birchen (ER).
It would appear that the colouration of Norfolk Greys (in conjunction with chick colour and leg colour) would be consistent with non-melanised E rather than birchen - and it would be interesting to see chick down colour of Dark grey OEG (I suspect this would similarly be the case).
As Christian has pointed out, silver sussex have a lot more silver (including breast lacing) than this colouration - if the suspicions of this colouration in Dark grey OEG are correct, this would be an example of how two phenotypes can be rather similar, but have a very different genetic foundation.
Cheers,
Htul