Pritchard bayonet for mkvi Webley pistol which also used buttstock of Webley flare launcher.
Originals used French 1873 Gras bayonets that were cut down. Originals with provenance are pretty rare and very pricy.
Pic from Royal Armories.
View attachment 10663
Old School is in session...
P229 - TLR4-G - Spyderco Citadel 92 Auto
Interesting. I could not understand why they built that design.