Manufactured by Clarksons of York, a Company no longer in business, this set of castings for a home-built light-duty drilling machine was then, for a time, supplied by Blackgates Engineering. The machine shown below was constructed during 1974 and 1975  using a Portass PD5 35/8" lathe, with the base casting being milled flat on a large miller in a technical college.
The column is 20 inches high in a bright mild steel (BMS), the table (six inches in diameter and able to be elevated through about 1 inch), the head, base plate (6" x 8.5"), pulleys, counterweight, motor mount, lever and H link are all in cast iron.
The spindle, 5/8" in diameter and turned from a 1" diameter BMS, has gunmetal bearings and carries a chuck mount threaded 3/8" x 24 t.p.i. 
The builder made a few modifications including a 4-inch longer column; a revised motor mount with a belt-tension quick-release sleeve (originally intended to stop the motor kicking upwards); the drive system changed from a single V-belt to a Poly-V; a larger 1/2" instead of 1/4" drill chuck and the spindle travel increased from 1.25" to about 2". He never got around to machining the six radial slots in the table.
Thanks to the builder, David, for providing the information and photographs.