Joe;
Interesting points you brought up there. This could & likely does, explain why the high grade guns mentioned had the lever on the right & my lower grade one had it on the left.
I believe that though built & proofed in Birmingham that this Clabrough built W Richards was built for the US market. Shooting with a pair of guns accompanied by a loader was/is virtually unknown in the US.
As to the lever jabbing me in the neck, well I am right handed but am not one who "Usually" carries my gun on my right shoulder while roaming the fields & forests when hunting. This would simply not be a concern to me.
For the uses to which I put a shotgun if I used a side lever I would definitely prefer it on the left.