I believe that the Masterpiece range has 2 features unique in the Grenson line: an oval cut-out on the lining which contains the model #, etc.; and a channelled sole (i.e. you cannot see the stitching on the sole, as it is hidden in a channel cut into the sole).
Are you sure that this sole isn't on the other Grenson line? Â Looking at the Grenson site, and comparing the models to those at Bennies, a few certainly do not look like Masterpieces. In fact a few look like from the line below it.
Some of the shoes are from the line below, for the most part the inventory is Masterpiece, however some are from the Footmaster line. Will be happy to tell you which shoe you got if you want to pm the style number and size we sent to you.