The Pritchard bayonet for the Webley revolver is one of the more photogenic and less truly practical weapons to come out of the Great War. Designed by one Captain Pritchard after he spent a year in France in 1915-1916 with the Royal Berkshire Regiment, the idea was to use the front 8 inches or so of a sword on a cast gunmetal hilt to create a bayonet mounted on a British service revolver. He first presented the idea to the Wilkinson Sword Company, but they were too busy making sabers and rifle bayonets, and suggested that having to sacrifice usable sword blades for production would make it quite the expensive endeavor.
Pritchard next took his idea to W.W. Greener, where he found a more receptive audience. Greener had a large supply of surplus French Gras bayonets, which were cheap and served as excellent donors for the Pritchard bayonets. Something like 200 were made in total - not formally adopted by the British but available for commercial sale to officers who might want them. While some may have seen service, no hard evidence has been found to prove any combat action with them.
Over the decades, a great many fake and reproduction Pritchard bayonets have been made - many times more than there are originals. As far as I can determine, this one is a legitimate original (although it may have a replacement locking lever). A few things to look for in authenticating a Pritchard are engraved patent and manufacturer marks (most reproductions have no manufacturer logo and a stamped patent number) and a quality casting. When you hold the blade and tap the handle with a hard object, it should ring bright and bell-like (which this one does).
WWI Hand Weapons: https://www.full30.com/video/ace5417ce327d3e4b27cc6c29607995b