There are quite a few Maidstone bottles made for the Maidstone brewery's. I'm guessing they were made in Maidstone... I'm also interested in Kent bottles in general as the area is local to me.
There was a huge tip in Maidstone just a few years ago full of stunning London, Kent bottles among other things, it was like a bottle diggers paradise but the land belonged to a farmer who got very angry because bottle diggers left huge holes all over the place and one of the farmers tractors had fallen into a hole, they made a right mess of his land. Probably still plenty more there although its a well known tip but I'd be careful not to cross paths with the farmer lol.