Well, it's a Westley Richards rook rifle - a nice one of the type built on a Martini action. I see this one is good out to 400 meters
(WR always seemed to psyche their customers up by putting really tall rear sights on their rifles.)
The ad copy of the day is very interesting:
http://www.rifleman.org.uk/Westley_Richards_miniature_rifles.htm.300 Rook was actually a centerfire cartridge, so having ammo made would be more possible than one of the extinct rimfires.
http://www.rifleman.org.uk/Miniature_calibre_cartridges.htm
