This trader advert from February 1951 shows the Strad Radios Model 510 and 5111 from R. M. Electrical Ltd.  The latter looks distinctly European in its design.  By July 1951 the 511 was at £19.15.3 from increases in purchase tax. The knobs on the 510 radio had strongly engraved horizontal lines:- which meant that they would always look out of alignment.

Strad does it again... 

Strad 510 has been specially designed to give increased gain and reduced background noise.  The attractive bow-fronted cabinet has unusual quartered grained walnut veneers and contrasting cream twin grilles and knobs.  5 valves, 3 wavebands, AC 200/250 volts.  Large 11½" Elliptical Speaker.  Cabinet 21" x 13" x 8½".

Model 510.  Retail Price £21. 15. 0. Tax paid.

... and again!

Strad 511 is the ideal inexpensive set for present-day conditions.  The styling of the plastic cabinet is original, modern, and pleasing to the eye.  Newly designed coils, ensure adequate selectivity and sensitivity.  5 valves, 3 wavebands, AC 200/250 volts.  Cabinet 16" x 10" x 8½".

Model 511. Retail Price £16. 16. 0. Tax paid.

It's sound - if it's Strad