Produced in several forms from the late 1920s until 1959, the Zyto brand was marketed for many years by S. Tyzack & Sons of 341, 343 & 345 Old Street, Shoreditch, London, a large retail mail-order company. Established in 1843, Tyzack not only supplied a vast range of engineering equipment, but also common household goods of all descriptions. Although the final advertisement for the Zyto lathe appeared in the model-engineering press during December 1959, sales trickled on into 1970s as stocks were used up. Ted Jolliffe, later to become editor of Model Engineer Magazine, owned a Zyto and recalls visiting the works in the early 1970s when serving as a policeman. Curious that a "copper" was keen on engineering, they took him under their wing and showed him round what was left of the factory, then down to two employees, with one acting as foreman - a situation mirrored almost exactly at the Portass lathe works 160 miles to the north, in Sheffield. Several items of woodworking machinery were under construction (possibly on a sub-contract basis), the basement held a good stock of raw bed castings and, in the fitters' shop under the railway arches, were stored enough spares to enable the manufacture of many more late-model lathes. Although all the castings had been sourced from an outside foundry, machining and building operations were kept completely in-house. On one visit, the MD pulled the covers off a long-bed lathe that, although it had never progressed beyond the prototype stage, had, he said, been loaned to Cowells, who were considering revamping the design and putting it into production. Looking to the future, Ted acquired a number of parts, at a suitably large discount, that keep his lathe running well into the 21st century. A Zyto horizontal milling machine was also offered, though examples are few and far between and no advertising literature has ever been found. Similar in layout to the more common Pools (and identical "Bond's O' Euston Road, Ltd.") the Zyto was unusual in being offered on a cast-iron stand, all the other versions being for bench mounting.  While "Zyto" lathes had, generally, a very mixed pedigree, the origins of the breed can be traced back to a 1926 Model Engineering Exhibition advertisement for the Billing Tool Company of 101 Clerkenwell Road, London, who offered a range of items for the model engineer including bench drills, 3-jaw chucks and a fast-and-loose-pulley driven Universal Sawing, Boring and Grinding Machine. However, their most important offering was bought in from the Portass Company in Sheffield, the Model XL being badge engineered as the  B.T.C. "Supreme". A simple little  3" x 12" gap-bed, backgeared and screwcutting lathe it had a full-nut leadscrew with a dog-clutch and a single swivelling (but distinctively T-slotted) tool slide. In 1927 Tyzack took a stand at the same exhibition and, obviously seeing some potential in the design,  announced the acquisition of the Billing company and the re-branding of the B.T.C. Supreme as the "Zyto". The machine was described as "The latest all-British Production" and available for £7 : 16 : 6d, exactly one shilling less than Billing's price the previous year. Portass was also kept busy supplying machines for other retailers to re-badge as their own and examples have been found marked: Altona, A.T.M., B.I.L., Bond's Maximus, Companion (sold by Johns in Auckland, New Zealand), "Eclipse" (for the Sheffield hand-tool makers James Neil & Sons), Enox for an unknown distributor or retailer,  Excell, G.A. (George Adams), Gamages, Graves, James Grose Ltd. of London (the latter chiselling off the Portass name and substituting their own badge), Juniper, Randa, Temmah, Wakefield, Woolner and Zyto, All appear to have been based on established Portass models, nearly always a version of the "Junior", the X and XL and later the venerable "S Type". However, in nearly every case, some small differences, usually down to cost-cutting, can be found - though it is possible that some examples were not made by Portass, but copied - one Portass advertising sheet claiming: Beware of Imitations. Portass lathes are being systematically copied and marketed and purchases should be careful to ascertain that the maker's label is attached to the machine.

A year later the price of the B.T.C. Zyto had risen to £8 : 2 : 6d, but this did include, due to the increasingly difficult economic conditions of the time, interest-free terms for what was referred to, in the gentlemanly terms of the day, as "deferred payments". Despite their new model, in late 1927 Tyzack announced yet another Zyto, at £7 : 17s : 6d , a 3" x 12" gap-bed, backgeared and screwcutting type - also made by Portass in their busy Sheffield factory (an original. However, the original continued to be made - with both offered alongside each other throughout the 1930s with little or no changes to their specifications. However, by 1937 the original lathe was very dated and a thoroughly revised version was introduced, probably shortly after the new "Super" went on sale. Although both early and late models are easily recognised (and the latter still commonly encountered today - though the former is rare) there were also two other types that sometimes lead to confusion: the smaller was a backgeared, gap bed, screwcutting version of what was to become the 3-inch centre height and 13 or 18-inches between centres Portass Model S and a larger model, probably only sold for a sort time during the mid 1930s, the "Super Zyto" - a machine with its bed and headstock cast as one (the "Super" name was revived for a short time during the 1950s when it was applied to a version with 16 inches between centres). Although the "Super" offered no improvement on the 3-inch centre height or between-centres capacity of the ordinary Zyto, it did incorporate numerous improvements including a compound slide rest, set-over tailstock, clasp nuts on the apron and a quick-feed rack-and-pinion drive to the carriage. The Super Zyto was also manufactured for Tyzack by Portass in Sheffield and, although it never appears to have been sold badged as a Portass, it can, actually, be identified amongst the company's products in the bottom right-hand corner of the only known picture of the complete Portass range.
In the mid 1930s the ordinary Zyto cost  £8 : 2 : 6d, and the "Super" £9 : 9 : 0d, if a compound slide rest was added to the former to more nearly match the specification of the latter, its total cost  became three shilling and sixpence greater - and not such a bargain. As an interesting comparison, and an indication as to why it was so popular, the Myford ML2 (a 3" x 15" machine with a specification almost identical to the "Super") was offered at the same time for just £6 : 7 : 6d - a substantial saving of 33%.
Various other lathes branded Zyto, both larger and smaller, were also listed in Tyzack's general catalogue during the 1930s, but these would have been bought in for resale and disappeared from later additions. The smallest shown was the Model F, a version of the simple, plain turning Sheffield-made Flexispeed; this was marketed both as the Tyzack Model F  and the "Small Zyto" with some advertisements offering the machine with the same double-reduction worm-and-wheel gearing fitted to the Flexispeed. It is known that when owners received their lathes some had a prominent "ZYTO" name cast into the front of the bronze apron while others were blank, with no identifying marks to be found anywhere. Tyack were not above mixing and matching parts from their other ranges of lathes, notably the larger IXL models, and occasionally a Zyto lathe will be found with a headstock, or other components, marked IXL. One Zyto, with a quite different (possibly home-fitted) saddle and compound slide rest has also been discovered carrying a badge with the letters "Leizure" arranged in a diamond-shape - but, again, no further details are known.
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Late 1920s to late 1930s "Standard" Zyto with bed and headstock cast as one
Although dimensionally very little different to the "Super", the "Standard" 1920s and 1930s Zyto model-engineer's lathe had many detail differences in comparison with its slightly more expensive brother: a 3-step round-rope "gut" drive was used on the headstock instead of a flat belt, the leadscrew nut was "full" (so demanding a dog clutch on the leadscrew to disengage the drive) the slide rest was a single swivelling type sitting on a saddle formed as a T-slotted  boring table (though a compound rest could be specified for an additional £1 : 10 : 0d) the tailstock handwheel was turned from the solid and had rather sharp edges while the handwheel on the end of the leadscrew was, for some unaccountable reason, a proper "balanced" type that must have been considerable more expensive to manufacture than a simple wheel. The range of accessories and drive systems was identical to that provided for the "Super".
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The "Super" Zyto"of the 1930s
Possibly made for them by Portass - though occasionally some elements of the lathe do not reflect that Company's normal practice e.g. some are found with spoked handles to the 16 t.p.i. cross and top-slide feed screws instead of the more normal solid type -  this version of the Zyto had bed and headstock cast as one with a centre height of 3 inches either 13 or 18 inches between  its No. 1 Morse taper centres. Bored through with a 3/8" hole, the spindle ran in split, parallel gun-metal bushes with a ball-race for thrust. Some examples have been found with a backgear at a 6 : 1 ratio, other at 9 : 1, in both cases using the same tooth form as the changewheels and of a conventional design that reached across the length of the headstock and allowing them to be slid sideways into engagement. Combined with the 3-step pulley for 5/16" wide flat belt, and using the standard motor-driven "fast-and loose" countershaft (£2 : 15 : 0d without motor) this would have given 6 spindle speeds from around 20 or 25 to 600 r.p.m. or so. While some most versions seem to have been fitted with backgear guards others, presumably lower-cost specials have been found without--the absence of screw holes to retain them showing that this is how they would have been sold. The makers offered both a cast-iron stand with a chip tray and treadle-powered flywheel (£4 : 4 : 0d) and a 3-speed "Foot Motor" (£2 : 15 : 0d) a self-contained flywheel assembly that could be mounted below the customers bench to provide a man-powered drive driven stand. When the final version of the standard Zyto was announced in 1937 (see the 1939 advertisement below) the centre height had been increased to 3 .375", a proper compound slide rest assembly was fitted (with a T-slotted cross slide, but still lacking micrometer dials) the dog-clutch on the leadscrew was replaced by clasp-nuts on the apron (with a handwheel n the leadscrew at the tailstock end) a tumble-reverse assembly fitted to the changewheel drive. Of course, with the full-nut on the apron gone, it was now possible to fit a quick-action rack-and-pinion hand drive to the carriage feed. The revised model was initially available with a very well designed but complex and expensive-to-produce self-contained countershaft fastened to a modified version of the cast-iron stand and complete with a Metro-Vickers motor fitted with a switch on its terminal box. Unfortunately, at £19 : 10 : 0d, this stand doubled the price of the lathe and there can have been few takers for a machine designed for the impecunious end of the market. Although some cheap lathes used weak, as-cast iron gears the Zyto came complete with a set  (2 x 20, 25, 30, 35, 40, 45, 50, 55, 60 and 65 teeth ) of properly cut changewheels mounted on a twin-slot bracket and able to generate most common English threads; a 63t wheel that would have given an approximate translation to metric screwcutting was an extra 7/6d.  Typical of the time for a small English lathe the cross slide was T-slotted, though its travel was very limited and thus its use as a miniature boring and milling table limited. The toolpost was of the usual triangular-clamp type, being simple but effective, whist the proper square-thread 10 t.p.i feed screws of both top and cross slide were, unfortunately, devoid of micrometer dials.
With the ability to be set over for taper turning the tailstock now carried a 5/8" diameter, un=graduated barrel with a No. 2 Morse taper and a square thread that ran though a cast-iron handwheel. Although shown with backgear guards in place, these were (on pre-war models) an extra costing 7/6, the same price as the rarely-specified changewheel guard.
Zyto lathes continued here and here