Nigel:

With regard to the rising bites, I don't have an opinion. After the Bissell was abandoned though, the later sidelock rifles were clearly Webley & Brain fasteners. I haven't taken any notes on their marks yet though.

Virtually all of their boxlock rifles were bought in. Most were Webleys, but other trade makers were used. I see one from Osborne on the market now, and saw one from Wilkes a while back. A friend and I are looking over a Rigby boxlock .303 right now. I'm stumped. Looks a lot like Wilkes, but isn't.

No, I've never seen a Rigby double with German proof marks. Lots of bolt rifles though. I've seen a few Manton DRs with German marks. There's one at Cabela's right now.