If you like double guns, you absolutely need a copy of "Spanish Best."
My copy is about 100 miles from here, but as I recall the story, the majority of the Basque gunmakers formed a consortium to achieve some economies of scale and to increase their market presence. A few companies stayed out of the consortium (AyA?), but when the Diarms consortium failed miserably, most of the very small makers just disappeared. That is why there are so many "modern" Spanish guns whose makers are no longer around. A small number of companies came out of Diarms and survive to this day.