Looking very much like a Round Bed Drummond (as well as the Fogg home-built round-bed) and fitted with a speed-reducing backgear, this is suspected to be a lathe built from a set of castings available during the 1920s and 1930s. Both before and a little after those decades, several designs for the home construction of a lathe were published in various magazine including the English The Model Engineer. Several machines of this type turn up each year, though none carry a maker's name, and it's a testament to the original builders that many are both well-finished and still in useable condition.
On the machine illustrated below, one puzzle is the 3-inch diameter, 31.75-inch long ground-finished bed - this surely being beyond the means of an amateur builder to grind. The most likely explanation is that this would have been supplied as a finished item.
With a centre height of around 4 inches - and taking up to 24 inches between centres, the lathe does have a tailstock and saddle looking very similar to the Drummond type, but with the T-slots in the saddle casting running (like the Fogg) from side-to-side not front-to-back. The tailstock spindle has a diameter of 7/8" with 23/8 inches of travel.
Unfortunately, the lathe has several small parts - but the owner reports that it turns with remarkable accuracy and is still a most useful machine.
Was it home-made, or factory-built? We shall never know - unless an advertisement extolling its virtues and glossing over the complexities of building it is discovered.
In harder times, it was not unusual for the makers of simple machine tools to offer their products as raw castings, or the larger items part-machined, for completion at home with known companies including E.W.Cowells (nothing to do with the better-known Cowells Small Machine Tool Company), Dore Westbury, Blackgate Engineering, Greenly, Senior and Firth, Haighton and Perris. Today, the situation continues, the Hemmingway Company in Bridgnorth offering a range of interesting projects for completion at home.
In the United States, the market for casting kits and plans was, of course, much larger and two small companies were set up to meet the demand, the David Jones Machine Co. and the Lewis Machine Tool Company who, between them, offered not just metal and wood-turning lathes, but a wide range of machines that included millers, shapers, mechanical hacksaws, bench and pillar drills, wood jointers (called a planer in the UK), bench grinders, spindle moulders and numerous other items including engineering workshop accessories. Another - but small-time - USA supplier was Honocast, with their simple little plain-turning lathe from the 1960s.