Interesting, thanks. some of those were real works of art. Professional hand-coloured photos were popular throughout the 50s in the U.K. especially portraits and a studio such as the one owned by Chambre Hardman in Liverpool had a small army of colourists( nearly 100% female and working for next to nothing) dotted around the city whereby a b&w portraitiwas taken one day processed and printed the same day then sent out to a colourist the next morning and might even have been collected the same day then framed if required. So maybe as little as 2 days between taking and handing over to the customer
I suspect that production of colour photos in this way was, at the time, cheaper and more reliable than an actual colour neg and print.
pentaxuser