Yeah, I don't know. I still don't think it's English. No drop points, hinge pin coming in from the right - this kind of stuff says Continental to me.
1861 is too early for a hammergun of this style from Purdey. I think their first breechloading centerfire shotgun was around serial #7000. These early shotguns were back-action guns with pinfire-style hammers. They had either Jones ULs or the first patent Purdey thumbholes on them. The Purdey bolt-Scott spindle style toplever came later.
And what about the dished out action around the lump holes? have you guys seen that before?
Why would you do that?
BTW:
Here's a Purdey from around the same time:
http://www.sitemason.com/files/ejbHNu/vms309a%20purdey12.JPGOWD
