Mondial machine tools were made by Mondial S.A. Constructions Mechaniques of Vilvorde-Bruxelles in Belgium. Their lathes of the late 1950s and through the 1960s were based on much-improved developments of their earlier "Simplex" models and included the "Celtic" and "Gallic" ranges all of which, despite some shortcomings of capacity specification, were considered to be very well engineered and soundly constructed. The original Celtic models were built as the Model "12" (6-inch centre height), Model "14" (79/32" centre height), Model "17" (81//1.9 H.P. for heavy-2" centre height) and the Model 20 (10" centre height).  Later versions lost their unpretentiously honest 1950s lines and simple rod control levers and were replaced by mechanically very similar machines with squared-off styling and flat control levers that ended in distinctive, triangular-shaped tabs.
The original 6-inch centre height by 20 or 32 inches between centres Celtic "12" was a robust machine intended for general workshop use, engineering training establishments and light production use. The lathe was mounted on two cast-iron plinths spanned by a deep chip tray and with option of two storage cupboards between the legs.
The headstock was divided (and stiffened) by two internal walls into 3 compartments: that nearest the spindle nose held the oil-bath lubricated reduction-gearing set (with an unusual dog-clutch in the form of a male and female "sprocket" arrangement); the centre part, which contained the twin drive pulleys, and was sealed to keep the V belts oil free whilst the left-hand section held the oil-immersed reversing gears that drove out to the train of screwcutting changewheels. At 1.04 inches the bore of the No. 4 Morse taper, Timken taper roller-bearing headstock spindle was markedly inferior to the 1.5" of the similarly-sized Colchester Student; the spindle was driven by 2 V belts from a 4-speed gearbox mounted inside the left-hand cabinet plinth and could be specified with either a 45mm-diameter, 3 mm-pitch thread on its nose or (standard on the high-speed model) a much safer and more rigid American long-taper L00 fitting. The spindle-speed gearbox was operated by a large chrome-plated lever on the front of the stand and equipped with oil-splash lubricated, induction-hardened gears running on ball-bearing-supported, hardened and splined shafts. Bolted beneath the gearbox was a push-button controlled electric motor fitted with 2 speeds as standard; according to the buyer's needs this could be specified as a low-power 1.3 - 0.9 H.P. for educational and training establishments, 2 - 1.6 H.P. for general-purpose use or 3 - 1.9 H.P. for the special "high-speed" model. Combined with the single-lever operated headstock-mounted "backgear" assembly the drive gave a total of 16 spindle speeds that spanned 35 to 1500 rpm on the standard models and 45 to 2000 rpm on the high-speed version. Although a spindle clutch was not available on any of the models the high-speed lathe was fitted with a powerful foot-operated brake on the drive pulley of the speed-change gearbox; it was applied by a full-length bar between the stand legs with its initial movement arranged to switch off the motor.
The V-ways of the bed were of a design similar to that first seen on the beautiful American Wade No. 7 precision bench lathe where the (asymmetric) front V was both laid back at a shallower angle than normal and made especially wide;  the rear surface was narrower and, in order to better absorb tool thrust, set at a steeper angle  Although not hardened (a process restricted to the extensive options' list) the bed was of robust construction and relatively deep in relation to the machine's centre height. No gap was fitted, nor could one be specified as an optional extra.
With every thread or feed selection made by rotary levers (and a consequent absence of sliding controls) the oil-bath screwcutting and feeds box (with hardened gears) could be completely sealed against the ingress of dirt and swarf. By using just the ordinary set of changewheels the box was able to generate 54 English pitches (from 96 to 15/8 t.p.i.) and 27 metric (from 0.25 to 10mm pitch) - a specification rather better than the 45 English and 12 metric pitches available on the standard Colchester Student. The sliding and surfacing feeds totalled 54 from 0.0021" to 0.128" per revolution of the spindle on longitudinal travel and from 0.0011" to 0.064" on the cross feed. With different changewheel set on the quadrant arm a complete range of diametral and module pitches could also be produced and the 5-segment screwcutting chart included these thread sets in its layout. The 4 t.p.i. leadscrew was ground finished for accuracy and its bronze engagement clasp nuts made adjustable for backlash; the power feeds were taken to the apron by a separate keyed shaft working though a torque-limiting coupling that also, very usefully, permitted work to be turned against stops.
With its double-wall construction, oil-bath lubrication and ingenious mechanical design (borrowed from larger Celtic lathes and long a tradition of the maker) the all-helical-geared apron was, some might argue, over-engineered for the lathe's capacity. The drive shaft from the gearbox transmitted its power through a worm and wheel to a shaft that passed vertically though the centre line of the casting; at the top of the shaft a double-sided dog clutch (operated by a very large combined selection and engagement quadrant lever on the face of the apron) moved up or down to select power surfacing and sliding feeds respectively - as reference to the illustrations below will make clear. Although the whole apron was a robust and reliable piece of engineering its feeds engagement mechanism suffered from the usual drawback of all quadrant-lever operated systems: the awkward double action of pulling out the location plunger and swinging the operating arm sideways meant that an instant (and certain) disengagement of the feeds was impossible. A simple-action flick-in-and-out lever working in a vertical plane between fixed positions (and through some sort of overload protection) would have been much preferred in this situation.
The saddle was entirely conventional (without a T-slots in its top surface) and carried a compound slide rest with proper taper gibs that were adjustable, with the usual sensitivity, by a single screw at the front. Two plain non-T-slotted cross slides were available, both with a travel of 6.75": a standard version - unfortunately shorter than the slide that it ran on and with a cast extension cover at the rear to protect the feed screw - and a full-length one able to accommodate a rear-mounted toolpost and its support block. The top slide could be rotated only 45 degrees in either direction but was supplied complete with an indexing (through 8 positions) 4-way toolpost at no extra cost.
The tailstock was, perhaps, the weakest point of the lathe's specification for, although the (unhardened) 1.438"-diameter barrel was  "microfinished" its travel was short at 3.375 inches (A Colchester Student has nearly 6 inches) and the Morse taper was only a No. 2 when a No. 3 would have been more in keeping with the rest of the machine. The top section could be offset in the usual way for taper turning and the clamping lever was conveniently placed at the very top of the casting.
In short-bed form the lathe weighed 1230 lbs and as a long-bed 1520 lbs..