The HO Model had a single T-slot 22" x 6 ½" table with a surrounding coolant-collection trough, two stops on its front face and was lever-operated by rack-and-pinion gearing along its longitudinal feed. The design was intended to facilitate ease of use when jobs were mounted in jigs with one or more slitting or forming cutters being pulled over them by a cheap-to-employ female worker. The table travel was 12-inches and the operating lever (which could be mounted at either the front or back of the table) gave 5-inches of movement for one revolution - though, of course, as it was impossible to make it rotate fully, the maximum travel that could be obtained by one stroke of the lever would have been less than three-quarters of that. Both the table cross feed and knee were screw driven with the former having 6-inches of travel and knee 7 inches (by a telescopic screw). The knee guide was especially wide but unfortunately this desirable state of affairs was gained at the expense of support - the 60º edges extending (as it did on so many cheaper millers of the era) beyond the width of the main column. Only a single clamp locked the knee, though it did have a good-sized, permanently-fitted handle.
The nickel-chrome steel spindle was ground-finished and ran in a roller bearing at the front and a ball race at the rear. The nose was bored No. 3 Morse taper and a draw bar held the 1-inch diameter arbor. Whilst most small millers of this era used a simple steel bar as an overarm (as did the next-larger Pallas in the range, the H.O.) the H.O.O. had a proper rigid cast iron assembly with a prismatic base that socketed into the top of the main column. The overarm and its drop bracket were both locked in place by levers rather than nuts - this seemingly insignificant point making the life of the operator or setter far more efficient for, with no lost spanner to hunt for when setting up a new job, valuable production time was saved.
Especially neat and completely enclosed the drive system consisted of a 1-h.p. 1400-rpm motor, with a 4-step V-pulley, mounted on an adjustable plate within the cabinet base and able to be reached though a large door at the rear of the machine; unfortunately the electrical switch was mounted on the left-hand face of the machine, dangerously out of the operator's reach. From the cabinet the drive went vertically by V-belt to an intermediate shaft running in bearings held within the rear section of a particularly deep, open-topped 28" x 23" cast-iron coolant tank sandwiched between base and main column. At the other end of the middle shaft the drive was taken up to the spindle from a 3-step cone pulley by a smooth-running flat belt tensioned by a jockey pulley. The 12 speeds, though without any form of gearing to help with slower rates, nevertheless spanned a very useful 160 to 2800 rpm.
A slot cut in the right-hand face of the base casting allowed a round belt, driven from the intermediate pulley shaft, to reach an externally mounted coolant pump.
Later versions of the H.O.O. were improved by the fitting of a more rigid vertical stop, a boss cast into the underside of the overarm to hold the coolant pipe in a more effective and vibration-proof position, the repositioning of the electrical switch to the front of the machine - and the addition of a script saying "British Made" to the column door. The H.O.O. miller required a floor space of approximately 26" x 23" and had a weight of around 1008 lbs.
Although most examples of Pallas millers encountered are marked "British Made" (usually on doors or other removable parts) others has been discovered labelled "Foreign Made"..