I doubt that Webley had much to do with this rifle. The shoe, block, and barrel all have regular Ordnance markings that were never cancelled as is usually done on a rifle that has been repurposed by a commercial seller. The brass triggerguard suggests that, unless this was a naval rifle, it is a cut down (sporterized) 3-band conversion (originally done at Enfield). At some point the Webley commercial lock was added. It probably has 3-groove, slow-twist rifling. I own (and shoot) a Webley 3-band Snider and it has no repurposed Ordnance parts although, as tiriaq mentions, it was probably only marketed by Webley and not actually manufactured by them.
milsurpo