From the early 1930s, this Britannia would have been one of the last made. It was available in two versions: the 6.5" centre height model had a 1.375" spindle bore and admitted 44" between centres while the 7" centre-height version had a 1.5" bore and took a generous 56" between the headstock and tailstock - or loose headstock, or poppet head - as older manufacturers called it. The lathe was available in a wide range of specifications to suit a customer's needs and pocket; the headstock was either "all-geared", or a simple, belt-driven affair, with a choice of adjustable bronze or taper-roller bearings and the feed to the leadscrew (via a conventional tumble reverse) could be through an economical 3-speed box (illustrated) - or a full Norton-type quick-change screwcutting gearbox with the ability to generate 33 English threads. 
Even though the makers offered a further option in the form a replacement headstock-end leg containing a motor-countershaft drive system with endless, automatically self-tensioning belts for the geared-head model, they still mentioned the availability of an old-fashioned treadle drive with "forged-steel arms". The separate power shaft for sliding and surfacing speeds, shown parallel to the leadscrew in the picture above, was also an optional extra.
Although of conventional appearance and construction, the lathe did feature one Britannia Trademark - an unusual toolpost base, just visible in the illustration above, that carried a wedge-like mechanism by which means the tool height could be set without the need to find loose packing

4.5" and 5" Britannia lathe with 20" and 38" inches between centres respectively.
The smaller lathes appeared almost as miniatures of their bigger brother, and retained the option of screwcutting by changewheels or a screwcutting gearbox - and with or without a power shaft for sliding and surfacing feeds; however, on this model, there was no 3-speed leadscrew gearbox available.
The bed had a "fixed" gap, able to swing 15" for the 4.5" model (Probably the Model "GO" ) and 16" for the 5", whilst the saddle arms were almost disproportionately long for the bed - although this would certainly have helped to even out wear along its length.

A small lathe, of obvious quality, carrying an aluminium plate proclaiming both "Colchester" and "Britannia". The twin raised Vees of the bed guide both the saddle and tailstock - the latter being of a most unusual pattern. The size and style of the micrometer dials would indicate a lathe built before about 1930, and possibly a lot earlier.

From the maker's catalogue of 1899 - showing the No. 2 and No. 3 lathe on its own special treadle-power stand.

This very early, possibly pre-1880, plain turning Britannia lathe Model No. 3 shown above and in the photographs below has an overall length of 29.75", a height of 5.25 inches and a bed 2.5" wide. The centre height is 3 inches and the capacity between centres 18".
The headstock spindle is carried in a single bearing - with its left-hand end held against a pointed support carried in an adjustable holder that fits into the space normally occupied by the left-hand bearing. This was a popular way, at the time, of arranging the headstock of a light-duty lathe and, despite its shortcomings, was a design that many makers persisted in using for several decades. The 3-step headstock pulley was not intended to use a V belt - it would be several decades before they appeared - but a round leather "rope", that is severely limited in the amount of torque it can transmit..
The tailstock is equally vestigial, though adequate for such a light-duty machine; two slender supports holding the barrel chamber. The cross feed handwheel in the photographs below is not correct - originally it would have been identical to that used on the top slide,.
When originally supplied that lathe could have been ordered in one of three bed lengths: 3 feet, 3 feet 6 inches and 4 feet; at an extra cost of £1 a gap bed could also be supplied.

The headstock spindle runs in a single bearing with the left-hand end of the shaft supported against a hardened steel centre. Because the spindle is solid the No. 1 Morse taper centre is held in a screw-on extension piece which doubles as a simple catch plate for driving work between centres.

The headstock sockets into the bed ways - but is held in place by just a single bolt. The point which supports and acts as a bearing for the left-hand of the headstock spindle can be clearly seen.

A view beneath the compound slide rest. Note the cross feed nut, hard up against the end of the casting.

Though cast from a minimum of material the tailstock, was entirely adequate for so light a machine. Instead of the usual quick-wearing, Whitworth-form thread and hopelessly-inadequate screw-in barrel lock, Britannia gave their customers a proper square-form thread, an efficient barrel lock of the split-clamp type and a comfortably large handwheel.

The Britannia Nos. 2, 3 and 6 plain-turning lathes were described by the makers as being suitable for, "Amateurs, Jewellers, Dentists or any Light Use."
The No. 2 lathe had a 24-inch long bed that allowed 14 inches to be admitted between the centres - that themselves were 2.5" above the planed, cast-iron bedways. The cost of the basic machine was £1 : 15s : 0d. - but when fitted to the cast-iron stand with its tool drawer, polished wood top, treadle assembly and 18-inch diameter flywheel this rose to £3 : 10s : 0d.
The No. 6 lathe, somewhat displaced in the model numbering sequence, was Britannia's cheapest offering at £2 : 15s : 0d and came complete with a treadle stand. In appearance the No. 6 was identical to the No. 2 - but with a shorter bed admitting 11 inches between centres.
Photographs of a No. 3 lathe can be seen here.

Britannia Lathes 2, 3, 4, 5 & 6
Britannia lathes closely reflected the standard design practices of their day, that is, they already had many of the features of lathes that would still be in production a hundred years later - but were of a comparatively light build. Because all the larger Britannia lathes featured a "plate", supported on twin posts, that passed across the left-hand end of the headstock spindle to absorb spindle-end thrust,  they (the spindles) could not be made hollow. The makers, with their Victorian training, must have assumed that the machines would have been largely used in the traditional way, with work supported between centres, and did not consider the needs of  the general repair shop or mechanic to whom a hollow spindle (or "mandrel" in contemporary language) would have been of great use. The increasing use of self-centring 3-jaw chucks also created a demand for hollow spindles and, by the early years of the twentieth century, Britannia, together with most other makers, followed the practice, established more than 50 years previously, of arranging for the spindle thrust to be taken on the inside face of the headstock casting, allowing the end of the spindle to be left and open and clear….
The smaller, plain-turning lathes Numbers, 2, 3, 4, 6 and 8 (illustrated on this page) had a headstock spindle carried in a single bearing - with its left-hand end held against a pointed support carried in an adjustable holder that fitted into the space normally occupied by the left-hand bearing. This was a popular way, at the time, of arranging the headstock of a light-duty lathe and, despite its many  shortcomings, was a design that many makers persisted in using for several decades. The 3-step headstock pulley was not intended to be driven by a V belt - it would be several decades before they appeared - but a round leather "rope", "gut band" or "cord" as it was variously called, that severely limited the amount of torque it was possible to transmit.
The lathes were designed for bench mounting, but were generally offered on a very slim, cast-iron stand with a treadle flywheel assembly; the design of this stand differed somewhat during the years of production with an even lighter assembly used for the No. 2 and No. 3 lathes.

The headstock pulleys of the No. 2, 3 and 6 lathe all had 3 belt grooves but, whilst the flywheel of the No. 6 lathe had 3 belt grooves to match, the flywheels of the other models all had 4. This  arrangement allowed the drive belt to be run at an angle from the flywheel to headstock - and so provide an extra two speeds. The belts could be joined with a variety of fasteners, from a simple wire hook to a quick-release twist fitting that, if properly organised, allowed an extra length of belt to be spliced in allow even greater cross-over angles from flywheel to headstock pulley.
The No. 3 lathe was a little larger, the bed being some 6 inches longer and the centre height increased to 3 inches. The stand and treadle were identical to those used on the No. 2 lathe, but the flywheel was made 2 inches greater in diameter and a little heavier. The price was £2 : 5s : 0d as a bench model, or £4 : 5s : 0d. on the treadle stand
A gap in the bed was optional for both the No.2 and No. 3 models and cost an extra 10 shillings - however, at this price, this gap did not bring with it a new bed of deeper section; instead, a small portion of the bed was simply cut away in front of the headstock…..
Both models could also be ordered, for £1 : 10s : 0d extra, with its headstock spindle and bearings in hardened steel.
Backgear was also available on the No. 3 lathe but, as this involved an entirely different headstock with two

spindle bearings, and the end thrust taken by a swan-neck casting bolted to the end of the bed (the arrangement can just be made out in the picture above), the cost almost doubled to £4 : 0s : 0d. When fitted with backgear the lathe could also be specified with a heavier pattern of bed, based on that used for the No. 13 lathe, where the section that bowed downwards as it approached the headstock held a proper detachable bridge - and all for an extra charge of just £1.
Besides the maker's self-contained treadle stand, a "foot-motor" was offered so that the owner could make his own mounting arrangements - yet still enjoy the benefits of human-powered turning.
With the basic machine, the first owner received two hardened centres, a driver chuck or catchplate for between centres work and a hand rest with two different lengths of Tee.
Detailed photographs of a No. 3 lathe, as well as can a version on a different design of stand, can be seen here,

The No. 4 Britannia "Improved Foot Lathe" was available with centre heights of 3.5, 4, 4.5 and 5 inches, and in bed lengths of  36, 42 and 48 inches - the 36 inch bed accepting 18 inches between centres. It was the smallest of the Britannia lathes to bolt directly to the legs of its stand rather than having bed feet to allow bench mounting.
This was a much more expensive lathe than the No. 3, costing some £8 in basic form and as much as £11 : 10s : 0d in long-bed , 5-inch centre height form. The machine was supplied from the factory on a treadle-power stand with an adjustable hand rest with two sizes of T, two faceplate (large and small) a pair of centres, a spanner and a wooden tool-table fastened to the back of the stand.

Plain-turning, light-duty Britannia lathe No. 5 shown with the optional backgear.
The centre height could be 4, 4.5 or 5 inches to order and the bed 48 inches long.
Because backgear is fitted to the headstock, the spindle (unlike that on the lighter version of the lathe illustrated here) has two bearings, but with the thrust still absorbed by a ball bearing held within a plate retained by two long studs at each side of the left-hand bearing.
When used as a metal-turning lathe, the backgear assembly would have substantially improved the versatility of the lathe - and allowed the operator to overcome, to some extent, the severe limitations on rates of metal removal imposed by the round-rope drive.
The counterbalanced flywheel was supported on a long shaft and, in an attempt to reduce the considerable drag induced by running this in plain bearings, the makers fitted an unusual "three-roller" system at each end; this mechanism can just be glimpsed within the tailstock-end leg. Unfortunately, each of the rollers ran on plain-bearings shafts ……
The driving crank attached to the  flywheel shaft was positioned outside the left-hand leg (Britannia called the legs "standards") and was fitted with a slotted arm so that the operator, or his assistant) could choose to vary the leverage (and speed) applied to the job. The counterbalancing of the flywheel avoided the time-wasting situation where it stopped at "dead centre", and refused to turn over - unless moved first by a persuading hand or foot.
The smallest version, with a 4-inch centre height and no backgear, sold for £11 whilst the most expensive standard model, with 5 inches of centre height and backgear, retailed for £14 : 10s : 0d.
A different model, but still marketed as a No. 4, was available with a 5 foot long bed, 1 inch wider than the standard 4 inches (and of heaver section) that admitted 28 inches between centres.

An ornate, X-shaped diagonal bracing points to this being one of the earlier-pattern stands for the Britannia Nos. 2, 3 and possibly No. 6 lathe.