As 'Batmen of the World' members, it's possible that they may have visited Gotham at some point. I think the point was more that he knew they were competent and trustworthy. Someone should post a collection of Knight and Squire scans - they're interesting characters. They've progressed beyond 'incompetent waffling British versions of Batman and Robin' to become the one B&R analogue that the general public might possibly have heard of.