Gammages is just Swan & Edgar, with a different name, part of Fields Luxury Products in the same office in Arcadia Ave, London, same cheap watches.
I would imagine IW sell lot more.
I think IW got a lot of their customers into watch collecting, people who are new to watches and watch collecting, which is fine, but part of the problem for is they started with mostly decent enough watchmaking brands, Mathey-Tissot, Roamer, Swiss Military, Sturmanskie, Vostok Europe etc but have since flooded their shows with cheap watches from numerous brands, who get their watches from China, that have started up to take advantage of/cash in on the renewed interest in watch collecting, with pretendy con artist experts spouting invented back stories (History & Heritage) and false quality claims who are just taking advantage of those new to watch collecting and less knowledgeable.
While there are a lot of microbrands starting up these days, quite a few of them are actually trying to provide a good quality watch, with decent movements etc, watches that are actually worth spending money on and adding to your collection, unlike most of the new brands on IW which are just cheap Chinese watches with the cheapest movements on the market, given ridiculously high RRPs and totally false quality claims.