I agree, it is wise not to discount it as a poss vallauris, I have a large plate too somewhere...
But have not found it since 'the move' that to has the back stamp but others I have seen have nothing at all. I guess it was down to the little man with the stamper thingy as to weather he stamped or not!
Not bad for ?5 at a boot sale!! Seller thought it was only a couple of years old He he!
Do you have anymore of that set? Or just the bits in the photo?