This has brought back memories. I would spend hours in Patstone & Cox browsing all the lovely things I couldn't afford. I had forgotten till I saw this. Beautiful little gun. Reminds me of a folding 410 I once owned.
I have my grandfather's Rook rifle chambered in .380 Rook and still break it out once or twice a year for a few shots. Mine is a break action operated by a button under the breech. I believe it's a Rook no.5
A very lovely rifle. the .300 Rook is more than adequate to the task at hand and joy to shoot. My grandfathers Cogswell & Harrison .300 Rook Martini uses much the same load, but instead of Black-Powder we use a handload of 10-grains Hodgden Triple-Seven BP substitute over an 80-grain cast Lee bullet. it is pleasant to shoot and will place 5-shots into the 10-ring at 50-meters.