Hi All,
Comparing this bike with original publicity shots, it looks to be a 1920's TS model - maybe even as late as 1926. The frame hasn't got the bracing to the top of the steering head, so is probably post 1918 - also the upper rear stays are bolted at the rear end, just above the wheel spindle (pre 1915 frames had the stay welded). Another dating point is the rear stand pivot being bolted to plates under the rear stay instead of into the side of the tube. Also, that design of rear carrier doesn't seem to have been used on 2¾ HP models before 1919.
Eddie.