And, talking about some children that were used as models for the illustrations, one of the interviewees mentioned ‘Magnets Bulbs and Batteries’.
I had forgotten all about that title, but a copy of that Ladybird Book was one of the childhood inspirations that got me into electronics.
I also remember that the page on series connection had a string of three bulbs connected in series, and that the one nearest the positive battery terminal was the brightest, and the one nearest the negative terminal was dimmest – so either the artist was given an odd set of bulbs, or someone thought that electricity ran out as it went around the circuit….?
The image is taken from Amazon, where you can buy the book.