Brian Perris, founder of Perris Lathes, was born in Bradford but started his engineering career in the early 1960s with the famous Metal Box Company in Portslade, near Hove. Leaving to start his own business in about 1963, he had a workshop for a brief time in Shoreham, followed by premises in Worthing before finally moving to Norwich. The Perris Company occupied two sites in Norwich: one at Roundtree Way, Mousehold and then a much larger factory unit in Sprowston Road. Mr. Perris began by making his own wooden patterns, based on the Flexispeed lathe he was then selling as kits of parts - a friend having bought the company. The Sheffield-made Flexispeed had its origins in the 1940s and was a popular small machine that continued in production, in various forms, for nearly fifty years. Over many years, and several changes of ownership, the Flexispeed became in turn various models: Simat 101, Meteor, Hector, Norfolk, Perris and then, unchanged, as the first "Cowells" lathe - a brand that was to find considerable success and which still continues in production today.
Known as a happy place to work, with the genial Mr. Perris in personal charge, the end came suddenly with the staff arriving one morning in 1976 to find "closed" notices on the factory doors - the death of Mr. Perris, as he was returning from an exhibition being sufficient for the creditors to cry enough. Besides marketing a version of the tiny Norwich-built Jason (as the "Pixi") the Perris appears to have been built as two main models: the PL90 "Modelmaker" with a cantilever bed and a version developed from it which, while generally of the same layout and sharing many parts (and obviously a Perris) was a tidied-up and rather better-looking design, the backgeared and screwcutting PL100 (shown lower down the page). The PL90 could be had as the SL, a backgeared but not screwcutting lathe or, as advertised in the May, 1968 issue of Model Railway News as two cheaper plain-turning versions, the "Standard" and "Special" at  lower prices.
However, other varieties were also offered, with as many as five versions of PL90 lathe (dating back to 1964), have been identified being sold using Perris, Ace Minor ,and Centrix Micro branding. The first to appear was the Ace Minor, sold by Urquhart Tools (a dealer better known for marketing machines using the "Astra" brand), this being reviewed very favourably and advertised in the ME for January, 1964. The range also included a bizarre Centrix, a machine with back-gearing but no screwcutting that, judging by the few encountered, must have sold in tiny numbers. Also offered for a short time - and today very seldom found - was a simple bench-top vertical milling machine
There is some confusion over the names 'PL90' and 'SL90'.  This seems attributable to Brian Perris initially selling the SL90 as the 'new' PL90, this terminology eventually being dropped in favour of 'SL90'.  The new SL90 type appeared ca. 1972 to replace both the PL90 and the PL100 and within several years the PL series was out of production - as expected by the manufacturer (the SL90 is the model Sid Cowell put into production in time for the 1977 ME exhibition, and of course Cowells has upgraded it since).
Clearly intended by Brian Perris to simplify the product line down to a single common platform, the SL could be made available in a number of guises rather than the previous situation of two basic machines with a number of optional extras - a situation that might have brought about a spare parts nightmare.
A brilliant fusion of the best features from the PL90 'Special' and the PL100, the SL90 was just three inches longer than the tiny PL90, but offered 8 inches between centres (the PL90 had just 6 inches and PL100 7 inches). The SL90 offered buyers a number choices, it being possible to start with a plain-turning model and then add backgear and screwcutting as finances permitted. Remarkably, so well designed was the SL that it could be refined to horological standards - a so-called 'horological' version of the PL90 was, apparently, just the 'Special'  - hardly of a watchmakers' standard in comparison with an SL90, but vastly superior to a Flexispeed and cheaper than the small precision Coronet lathes made for a short time after WW2..
A well-engineered, fully-specified lathe in miniature the PL90 was offered first as a kit of parts and later as a fully-assembled model. When supplied for home assembly it arrived fully machined with all holes drilled and tapped and with instructions detailing clearly how to assemble it correctly. It was constructed on a flat-topped, 60-degree V-edged bed of cantilever form with a 44-mm centre height, capable of accepting 200 mm between centres and a maximum diameter of 120 mm (by 19 mm thick) on a faceplate swung in the gap. It could be ordered as a simple plain-turning model, with no backgear or screwcutting, or with one or both of those extras supplied when new or later, as funds permitted.
Located by a tenon in the gap between the bed ways the headstock carried a 0.25-inch bore, No. 0 Morse spindle with a 0.5" x 20 t.p.i. u.n.f. threaded nose running directly in the cast-iron; the holes in the headstock forming the bearings were slotted horizontally and adjustment achieved by nipping the top section down with a clamp screw. Like all such spindle arrangements, common in  the miniature lathe world, great care has to be taken not to use these screws as a form of adjustment; over tightening will lead to fracture of the headstock casting and a difficult and expensive repair. It's far better to have new bearings made, and even a spindle as well if necessary, when wear has become apparent. A 3-step headstock pulley was fitted, designed to be driven by 5-mm diameter round plastic belt; depending upon the desired speed range it could be powered directly from an electric motor - in which case only very high speeds for turning tiny components would have been available - or through the optional speed-reducing countershaft that was mounted on an arm bolted to the back of the bed. With a remotely-mounted 1425 r.p.m motor fitted with a 1-inch pulley the countershaft gave approximate spindle speeds of 423, 750, 1333 in open drive and 89, 157 and 280 r.p.m. in the optional-extra, 4.75 : 1 ratio backgear.
For a miniature lathe the carriage was of heavy construction with an especially large (139 mm x 44 mm) three T-slot cross slide with 89 mm of travel (designed to make the most of mounting a vertical milling slide) and a 360-degree, 1.5-inch travel swivelling top slide located by an inverted conical boss with pusher screws entering from both sides of the cross slide. The friction-set zeroing micrometer dials were clearly engraved, fitted with knurled finger grips and with a useful if simply-constructed handwheel on the cross slide. The dials were marked with 40 divisions in mm graduations, each representing 0.025 mm of slide movement, or 0.00098 inches; the makers pointed out that as this was so very close to 0.001 inches it was hardly worth them making alternative screws, nuts and dials for the UK and other inch markets. The auto-traverse fine-feed attachment (a full set of screwcutting changewheels was extra) drove through a neat dog-clutch with engagement by a knurled-edge handwheels and disengagement through a useful (and safe) adjustable automatic throw-out. The metric-pitch Acme thread leadscrew ran through a cast-iron "whole" nut on the apron and so, with no quick-action rack-feed to advance the carriage, movements up and down the bed had to be by twirling a wheel (with micrometer dial) fitted at the leadscrew's tailstock end.
Well constructed, the set-over tailstock was clamped to the bed by a captive lever working on a cam and, with a 32-mm travel barrel and No. 0 Morse taper centre, was aligned (as on Series 7 Myfords) by ways cut vertically between the bedways.  Perris also made a jigsaw, the Jigsaw Master in Mk. 1 and Mk. 2 forms  - should you have one, the writer would be pleased to hear from you..
A highly detailed description of the Perris lathe can be found on this page, researched and written by that great enthusiast for tiny lathes, Andrew Webster in Canada..

The less-expensive Perris "Special". PL90 Model Maker's lathe - a version marketed exclusively from the factory. Note: the proper compound slide on a tapered spigot; a two-T-slot table, (unlike the Centrix which had three); an 8 mm collet-type 1/2" x 20 t.p.i. Mandrel; the SL90 tailstock (self-ejecting centre with a proper locking mechanism and screw-adjust set-over and graduated micrometer collars on top and cros slides - the latter having the facility of being adjustable to zero (the Standard version of the Perris PL90 seems to have been the one with a 1/2" BSF nose, 0-MT sockets in headstock and tailstock, a rather crude bolt-down top slide and a bolt-down tailstock etc., exactly as the Centrix.

Perris Model PL100 (in effect a PL90 Mk. 2). With a Myford-like extension to the cross-slide end bracket, a full-depth bed, enclosed changewheels, neatly-engineered dog-clutch on the  leadscrew and guarded belt drive this more sophisticated Perris lathe demonstrates considerable attention to detail.

The design of the backgear assembly resembles that fitted to the Pre WW2 Myford ML2 and ML4 lathes being clustered together on an eccentrically-mounted shaft behind the spindle-mounted bull wheel. The countershaft (that also carried the hinge bracket for the changewheel cover) was bolted directly to the back of the lathe bed.

A view showing the spindle-bearing adjustment screws, the unprotected bearing oil holes, the simple but robust robust-for-its-size layout of the countershaft and the neat if fragile arrangement of the changewheel cover's hinge assembly.

No tumble-reverse mechanism on the changewheel drive but ample room to build a proper compound reduction of gears to give a provide feed to the carriage drive.

For an inexpensive lathe the compound slide was particularly well designed and made. A Myford like end bracket enabled the cross slide to be moved until it was well over the front edge of the saddles (a great boon when using a vertical milling slide) the clearly engraved micrometer dials could be zeroed and the knurled edges of the handwheels (in lieu of handles) provided a secure grip that allowed tiny adjustment to be accurately made - even with oily hands.

Another expensive-to-engineer feature seldom seen on miniature lathes was the tapered spigot. mounting of the top slide onto  the cross slide.
Unfortunately the T-slotted cross slide of the PL100 was shorter than that used on the earlier PL90

Above and below: the tailstock was fitted with a proper through shaft carrying an eccentric lock but, unfortunately, a simple split in the casting to close down and lock the barrel.