For many years I drew a monthly picture for the BBC World Service listings magazine BBC Worldwide, later renamed BBC On Air. This was a happy association with art editor Martin Colyer, which started at The Listener.
In the early days (mid-Nineties) I drew a black and white picture and marked up on an overlay areas that should be colour. The markup would be in percentages of the printing colours, eg C20% Y50% M30% K10%. (I imagine that adds up to a dog-turd colour.) This was extremely hit-and-miss, and Martin later admitted he always had to tone down the results. By the end of the century I was colouring in with a few clicks on Photoshop.
The black-and-white original of the wine-quaffing Cole Porter was bought by Tony Mason, the manager of Majestic Wine, a little local company which commissioned a few drawings from me in early Eighties. It later became a big company.