I would like to know what Martin Silverudd used to create them. I've seen Rhode Island Red, New Hampshire Red, Crested Cream Legbar, and Australorp thrown around, but how did he get rid of the crest?
Getting rid of the Legbar crest is easy enough. Breed to a non-crested bird, get crested chicks. Breed those chicks to a non-crested bird, half of chicks will be crested and half will not have crests. Use the non-crested ones from that generation, with other non-crested birds, and you will never see another crest.
How much Australorp do you have to add to get rid of all that red and barring? Can't be too much if you want to keep your blue eggs.
If you want to keep the blue egg gene, you can add almost unlimited amounts of other breeds. Cross a Legbar to any breed without a blue egg gene, and all chicks should have one copy of the blue egg gene. Those chicks will lay blue or green eggs (not white or brown.)
After that, you can do unlimited generations like this:
Cross a female who lays blue or green eggs to a rooster with no blue egg gene. Raise up some daughters, and about half will lay blue or green eggs, while the rest lay white or brown. Choose some of the daughters who lay blue or green, and repeat the process as many times as you like.
You can do both of those things at the same time (get rid of the crest AND keep the blue egg gene while breeding with Australorp or another breed.) First generation from Legbar, all chicks have one crest gene and one blue egg gene. Next generation, some chicks have crest and blue egg gene, some have just one or just the other, some have neither. Choose the ones with blue egg gene but no crest. After that, you just have to keep track of the blue egg gene when you do crosses, because the crest is gone for good.
I think we are missing a big piece of the puzzle.
The gene for blue feather color needs to come from somewhere (maybe blue Australorps?), but as long as it comes from somewhere I don't see anything impossible in that list of foundation breeds.
