Mike - that is a good catch!

As expected from an early(ish) rifle the high hammers and non rebounding locks are standard form

With stalking safeties and the full rose and scroll engraving (my personal favourite) whats not to like

It looks like a W&C Scott made rifle (more than Philip Webley) who between them made almost all of H&H guns and rifles at the time (Before H&H built their own factory in 1892/3)

My .500 BPE H&H is less good, plainer with flat hammers, early with non rebounding locks like yours
Not sure if it is the other maker ( In am not quite sure about the differences)

The .450 3 1/4" cartridge of the time could be had with a 365 grain bullet ahead of 120 grains of BP would drop any thin skinned game (note the Martini Henry with albeit heavier 480 grain bullet ahead of 85 grains BP was used on all game including elephant) before the prohibition of the .45 calibres in the Empire

good luck shooting it should be easy to load for, not sure about regulation

I am most jealous of you guys in the U.S. and elsewhere who can just go and shoot these beauties a where it is safe

Best

Tony