I found a good explanation of English blue in an article on Gotland sheep, English blue is co-dominate with katmoget, gulmoget, and gray agouti gene. The parents each contribute a gene for color and a gene for pattern so the possibilities are endless.
My neighbor starts lambing in May.......if there is a promising polled Icelandic ram lamb will get him .I will find a stocky well built ram and then look at the color. Every color and pattern will be available, as she has 50 ewes lambing bred to White, Black and a Spotted ram, Alot of the ewes having the agouti gene so have "pastel" coloring
21 hours ago