sorry but can't help with attribution - although your comments regarding scratched Nos. on the stopper might possibly be the factory matching nos. If you look around the area of the top/neck, alternatively possibly in the area of what you are describing as the "polished pontil mark", you might find identical nos./marks to match those on the stopper. If it was blown into a mould, then it may possibly not have a pontil mark - are you able to find seam marks on the body (indicating it was blown) - and if possible, may we see a picture of the base of the body please
