On the majority of Morris cars the knobs on controls such as the slow running, choke, starter, etc.. have engraved letters and words which were originally filled in white. Over the years the white filling has discoloured or completely disappeared. Here is a good tip for which acknowledgement is due to the Ford Y and C Model Register.
First take a sharp pointed tool such as a bradawl and trace out the original engraving and remove away remaining old white filling. The next move is to a a jar of ‘Tipp-Ex’, ‘Liquid paper’ etc… white correction fluid and generously apply in and around the engraving. After leaving the Tipp-Ex to set hard, scrape off the surplus leaving only the white words. It is advisable not to use a too sharp an instrument on for this, the writer uses his thumb nail. The final touch is to use a little metal polish to the surface and wipe off with a soft cloth. The final finish will amaze you.