My guess is that "Nobby Hall" began as an adolescent parody of "Sam Hall." "Sam" is concerned with a defiantly unrepentant character. "Nobby," however, is more concerned with naughty rhymes - or ostentatiously avoiding naughty rhymes.

I don't think the word "wank," which features in "Nobby," was much used before WWII.

FWIW.