"Opal blue"

[Colin Morgan]

Prior to the 1950s, when dye-stuffs were invented by ICI, there was a limited range of basic colours available. Perhaps the different blues achieved by mixing one basic blue with other colour paints? (I seem to remember seeing lists of some of the mixes used.) I don't know if this helps - but it might be that it was all a lot simpler back then and few options for creating a different colour?

Back in 2013 when paint colours were being discussed on here, Martin Prior suggested contacting a company called Jawel Paints of Wolverhampton as at that time they apparently had records of prewar Austin paint mixes.