I was in London for a brief trip over the weekend and visited Purdey's Audley House in central London. They were incredibly pleasant and accommodating even though I made no purchases. I would have considered some snap caps, but I didn't see any out. If you are passing through, I would recommend a visit. Thought I would share some pictures. There were a couple of interesting guns on display including a one of four Schmidt triggerplate action gun and a four barrel (both under over and side by side, I guess).
https://imgur.com/a/purfey-audley-house-aBGcYBY
