The broad interwar market for British warship designs

Were third powers beyond the Dominions buying British warships during the interwar years?

Yes; British firms supplied many countries directly or through foreign yards and designs, including Spain's Vickers-linked Canarias program.

The market for British warships extended to South America, Thailand, Portugal, Poland, Estonia, and Spain. Estonia's acquisition of British submarines is one example of a direct export relationship. Spain's Canarias-class cruisers were built domestically, but their yards were owned by Vickers, so British industrial influence remained central. Export history must follow ownership and design networks as well as the flag over the completed ship.