a stamp with the crown of William IV, used later as well
Marks that can be entered for this maker: Model, type or typology, Tang stamp / makers mark, Blade code, Era marker / packaging.
Nothing predates 1830; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: web.archive.org