Regarding colour standards as has been commented BS381 (Colours For Specific Purposes) first appeared in 1931 and BS2660 is also of prewar origin and RAL also has it origin in standards laid down before WW2. Organisations have insisted on the use of colours matched to standards for some time. For example, Military aircraft paint schemes in WW2 were matched to colours laid down by MAP and paint manufacturers were expected to quite closely adhere to those colours, although weathering could alter them due to supply issues with the pigments used. In the 1950's the Israeli Air force specified surface finishes matched to RAL. Now those paints will have been manufactured matched to a standard, it might have not been to modern computerised standards, but would have been a reasonable match. On a model if it is known the paint standard used, it is not unreasonable to use that colour if there is no evidence it was supposed to be a different colour.