OK, I've just re-read this thread, and will need to be reminded of the circumstances that define this rifle as made by Alex Henry.

It doesn't have Henry rifling, strange but not impossible, and doesn't have the characteristic cheek-piece of Henry double rifles of the period. Last but not least, the serial number appears not to fit a Henry.

Have I missed something?

I'm tending to agree with Point 1 in Saku's post above.