It is really not that confusing! I promise, LOL.
I remember you posting about these birds before. I never told you that bird was Blue Fawn. The other bird you have or had that looked the same, but had the slight blueish grey cast was the Blue Fawn, not this one. This bird I believe we all told you previously was a Grey (again, in the US we call the color "Grey", but in the UK, you refer to it as "Mallard"). What none of your birds are, beyond a shadow of doubt, are Trouts. Trout is a completely different color. It is Grey/Mallard plus light phase and Trouts are much, much lighter in appearance. I remember that RevolutionMama had posted a picture of a Trout for comparison. They look completely different.
Now, as the bird in question has feathered out in adult plumage, it is more obvious that he is mixed color. In very basic terms, all duck colors are built on a particular color pattern. A bird inherits one gene from each parent for whatever pattern (Wild-type pattern, dusky pattern, restricted mallard pattern). If the patterns of the parents are not the same, birds like yours result. In his juvenile plumage, he looked more like a Grey/Mallard (wild type). In his adult plumage, he shows obvious signs of dusky (no neck ring, no claret). This just means that one of his parents was the wild type (known as m+) and the other was a dusky based color (m^d). I would not use him for breeding if color is important to you as his color is not correct for Mallard or Dusky, he is an off-color.
He definitely is not Trout and he definitely is not Blue Fawn. If you thought I was saying he was Blue Fawn, we were not talking about the same bird. I was talking about the lighter colored bird with the Grey/Blue tones.
