These sets were bricks that were laid just like the real thing with a water-soluble mortar and even 'scaffolding' that slotted into holes in the baseboard.
Bayko was invented by Charles Plimpton, a plastics engineer from Liverpool. It was originally sold in Britain and was soon sold throughout the British Commonwealth and became sold world wide from 1934 and 1967. The company was sold to Meccano in 1960 who stopped producing it in 1967.
The name derived from Bakelite, a fairly cheap commercial plastic that was originally used to manufacture many of the parts. Bayko was one of the world's earliest plastic toys and could be said to be the precursor to Lego, who only made wooden bricks until 1940.