Late 1930s to around 1946 Harrison L2 with a 4.5-inch centre height. Apart from its flat-belt drive headstock and lighter headstock-end bed foot it appears almost identical to the first of the geared-headstock models listed as the L5 Series.

Harrison Mk. 1 L5 - circa 1944 to 1948: 3/4" bore spindle running in plain bearings; a lift-off headstock cover with the letters "A" and "B" cast into the front face; micrometer markings engraved into the flat rims of the cross and top slide handwheels; cast-iron plinth under the headstock and a simple leg under the tailstock end of the bed (although some full cabinet stands in cast iron were also manufactured); flat-sided, triangular-form, bolt-on changewheel cover in cast aluminium; clutch operated by a bed-length horizontal bar. On this lathe the handle is missing from the apron-mounted clasp nut closer.

Harrison L5 Mk. 2 - circa 1949 to 1951: full-length cabinet stand fabricated from heavy-gauge sheet steel; roller-bearing headstock with a smaller bolt-on top cover with a raised rib around its lower front edge and a small spindle-speed plate between the "A" and "B" markings; conventional zeroing micrometer dials; large bolt-on changewheel and the belt cover cast in one piece with two curved faces to the front; short clutch operating lever pivoting on just the headstock.

Harrison L5 Mk. 3 - circa 1952 to 1956: headstock spindle with the option of either 0.75" or 1.25" bore; headstock cover without the "A" and "B" letters but with a larger spindle-speed chart often protected by a transparent plastic plate; large cast-aluminium combined changewheel and belt-guard with hinge-open gear cover; tailstock barrel clamp positioned vertically at the rear rather than horizontally over the top of the smoothed-off casting;; exposed spring and thumb catch removed from the apron-mounted power-feed engagement lever and its material changed from a bronze casting to a metal rod; leadscrew reverse control knob changed from solid steel with a knurled edge to plastic with seven finger grips; 3-speed feeds and screwcutting gearbox changed to an enclosed type with an upwards-pointing lever; Harrison name removed from the bed and relocated to a headstock-mounted plate.

Mk. 4 - circa 1957 to 1966: cross-feed and carriage traverse handwheels with 3 spokes and  internal finger grips; large speed-change lever on front face of headstock fitted with safety catch requiring the lever to be pulled out before it could be moved. This particular L5 is shown with a large-bore spindle with a threaded end - a rare combination that was discontinued after 1959.