Nice knife. Lettering on stamp marks became more affordable around 1810, prior to 1810 a lot of marks were just symbols- like peppercorns or crossed keys. The kick at the riscasso was usually square and rather narrow, the edge going almost to the shoulder bolster. The button on top, that style dates back quite a ways. Smith's Key 1816 shows Sheffield Knives of that style but the buttons were either round or shaped like the front sight on a Colt "Peacemaker" A lot of folks don't realize that rocker type locking blades are of an old, pre-1840 origin. Buck Knives didn't invent the Lock back. When the button is half way- its a mid-length rocker. The spring is the same as a slip joint with the front cut off and the spring pushes up against the bottom of the button. They're really pretty neat knives.
I'm not sure when clip point folding blades became popular. Maybe around 1850. Prior to that a lot of folders had more round tipped blades, bulbous or willow leaf shaped. Some French folders had sharp pointed blades.
Pre-1840 pocket knives are few and far between. A lot of "historic" friction folders are European grapevine knives from the 1920's.
On a Sheffield knife there is a Grand Poo-Ba over there controlling stamp marks, etc.- it doesn't seem to be a Sheffield knife to me.
It wasn't until about 1850 that inexpensive sheet metal and metal stamping advanced to a point that those materials started showing up in folders. When a bolster is applied to a liner, that's called the "Applied" method. Prior to that a lot of folders had a handle where the bolster and liner were integral and iron- made from trip hammers.
The date???? That's a hard question. It might be from the late 1800's or something only a few years old, but the style- seems much better than a great majority of the folders being used.