stoneware bowl (William Marshall) ??

A lovely green/blue/brown glaze bowl 12" wide x 5" high , made from a red clay with handles both sides , nice shape in A1 condition , it has a mark on the base which liiks like two diamonds joined one with a dot .. ive looked but cant find the marks !!
I love stoneware items and have quite a few pieces but never come across this mark before ..
I think I've just found the mark - William Marshall .
Bernard Leach's first apprentice ..
Very interesting!!