We used to have similar cotton-based cables here, usually as a covering for a rubber insulation. Thermoplastic is the standard now, with butyl rubber for high-temp. work.

When you used to use black/white "loomex" for a 208 or 240V circuit, I assume that the CEC required the white to be tagged black or red at each end ??

You'll find some of my posts for U.K. color coding in this section.