Looking similar to the well-known "Relm" lathes, the RSB might have been made by Breeds, in Leeds, a company with a connection to Relm and whose lathes were sometimes branded "Atlas". The only known surviving example, the machine shown below, is of 3-inch centre height and 12 inches between centres and would have been made during the first decade of the 20th century for the amateur market. The bed, very lightly constructed with thin walls, was of typically English style with a flat top, V-edged ways and provided with a decent gap.
Cast as-one with bed, the headstock lacked a speed-reducing backgear - though the 1-inch wide 3-step pulley unusually generous diameters of 2.5", 4" and 5.5" so helping to improve belt grip. Where simple and cheap split headstock bearings might have been expected (and cracked castings as a result of enthusiastic over-tightening), the RSB had a proper 2-bolt cap type with thin split bronze shell bearings that, on the surviving example, have survived the decades unworn.
Screwcutting was by changewheels mounted on an awkward-to-set-up, L-shaped bracket and through an unusually large diameter, fine-pitch leadscrew fitted with a large balanced handwheel at its tailstock end, a dog-clutch by headstock and a full nut bolted to the underside of the saddle - there being no necessity for a conventional apron. The full nut appears to have been split and fitted with an adjustment bolt at its lower end - an unusual addition on a lathe of this class (indeed, on one of any type). Unfortunately, where the tool thrust was taken out against the back of the bed, instead of a solid-to-solid contact, an adjustable gib strip was inserted to adjust the fit of the saddle, so introducing unwanted flexibility (the strip and its adjuster screws should have been at the front).
A single swivelling tool-slide was provided, carried in a traverse T-slot in the saddle - with two more slots provided that ran longitudinally down the right-hand saddle wings - so providing the makings of a handy boring table. Judging from the thickness of the saddle and top-slide castings, it's likely that sufficient room was available to fit a proper compound slide rest, something that the maker may well have offered at extra cost.
Of the simplest possible kind, the tailstock was a single casting - and so with no base on which to set over the top for taper turning. Fitted with a No. 1 Morse taper nose the spindle was locked by that horribly crude method, a slit in the casting closed down by a bolt.
If any reader has an RSB lathe the writer would be interested to hear from you..