Interesting indeed. Looks very fishy, and the colours make sense for the conditions and time grubs were intended for.
I just bought an old Farlow's Salmon reservoir, one of those black japanned cases with multiple trays. In there I found a gut eyed fly that has a Jock Scott body, with Crow and Toucan, but two slips of yellow Macaw for the wing, with two toppings over. No underwing.