"Perfectly secure" for the time.... maybe.

In the late 1800's it didn't take them long to figure out a double under bite is twice as good as a single under bite.

Another thing to consider when looking at an old 1860/70's Purdey...I don't think they were established as the "Purdey" as they were a few years later.

What I'm trying to say is I don't think in that time frame that they were the best of the rest.