Manufactured by Twin Engineering of Caxton Way, Holywell Industrial Estate, Watford, England, the "Twin" vertical miller was made in two distinctly different versions: the "Heavy", a substantially built stand-mounted model with a tilting head and the "Light", a smaller model with the head fixed in the vertical position, for bench mounting. Both were well-built, substantial machines and constructed in some numbers; they found their way not only into private workshops but also schools, training establishments and government departments - although despite apparently good sales this remains an uncommon make on the used market.
Mounted on a fabricated stand, the heavier model used a conventional cast-iron column with ways for the knee formed on its front surface. The knee was elevated by a front-mounted screw - in the manner of a Centec 2B - and carried a 20" x 6" table with two T-slots. Longitudinal travel was a reasonable 10" and the traverse 5.75"- remarkably generous for a small machine. The vertical movement of the knee was a 9"  and the maximum clearance between spindle nose and table a handy 12.25".
Carried on a circular boss, the head could be rotated 90 degrees in either direction from central and was driven by a rear-mounted motor through 4-step V-pulleys. Rotating on taper roller bearings, the spindle had 4 speeds of  520, 960, 1650 and (set usefully high) 2880 r.p.m. Although a quick-action handle, working through rack-and-pinion gearing was fitted, there was no fine feed for the quill - that and the awkward nature of changing speeds - being the only two drawbacks to an otherwise accomplished little vertical miller.
Of unusual design, the "Light" had a head, together with its belt-drive system, that moved up and down between widely-separated slideways formed along the front edges of the side faces of the main column. At the top, the faces were joined by a bridge piece that provided a mounting platform for the head-elevation screw. The belt guard, which covered the direct-drive from motor to head, could be raised at both front and back to ease the changing of speeds. Like its larger brother, even though limited to just 4 speeds, a good spread was provided with a range that started at a low of 520 through  960, 1650 to a high of 2880 rpm. The spindle fitting replicated the nose of a series 7 Myford with a 11/8" x 12 t.p.i thread with a No. 2 Morse taper - this arrangement allowing the use of  "internal" compression collets retaining by the same nose piece designed for the Myford. However, provision was also made to use a drawbar for heavier work involving a Clarkson-type cutter holder. A generously-sized table was fitted,  20" x 6", with a longitudinal travel of 10" and, for a small machine, an unusually long 5.75-inch in traverse. The vertical movement of the head was a 10"  and the maximum clearance between spindle nose and table 9.25". The "throat" (from spindle centre line to inside face of the column) was 8". Good quality, clearly engraved satin-chrome micrometer dials and large, chrome-plated balanced-ball handles were fitted to the table with a larger plastic wheel used on the head elevation screw.  The bench miller was 37" high, 36" front to back and 30" wide and, being of heavy construction, weighed approximately 320 lbs..