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I recently bought a Colt Thur derringer that had a Liverpool dealer and English proof marks. It seemed like it was set up for center fire. That prompted me to acquire an English .41 CF cartridge. The sleeve it came in was labeled ".410". Then I remembered that my Colt Cloverleaf also had British proofs and was marked ".410". I took a look at it and realize that the hammer is shaped a bit like the one on the Thur. That made me think maybe that my English-market Cloverleaf was chambered for center fire too. So, I took a 41 RF cartridge apart and put the case into the English-market Colt cloverleaf. It struck the cartridge between the rim and the center, making the mark on the right on the left cartridge in the picture below. There was no discharge. Then I took the same case and put it into my Model 1 National derringer. That gun made the mark on the left and did discharge the primer! I can tell that the hammer on my cloverleaf strikes down through the chamber. While it hit the lower margin of the RF cartridge, I am guessing that with the more thick-rimmed .410 CF cartridge it would have hit the raise primer in the middle.
It is know that there were Thur derringers that fired 41 CF. They are a rare variant mentioned by Flayderman, worth a premium, as are examples with marks from English dealers. However, Flayderman does not mention Cloverleaf pistols chambered for any thing but 41 RF short. I suspect I have a pretty rare pistol.
Marcus