Could have been anytime in the first half of the 20th century. Interesting usage of language and sentence construction.
Bring back the word "blatherskite".
And Gumbles!
https://en.wikipedia.org/wiki/Bottersnikes_and_Gum... probably explains my year 1 experience of being put in the rubbish bin by the big girls.
Reading the description of Gumbles doesn't quite tally with my memory of Gumble (the map)