Nowt is a dialect form of ‘nought’ = ‘nothing’, here used for the rhyme.
I should wait. When in doubt what to do, he is a wise man who does nothing.
[1874 G. J. Whyte-melville Uncle John xx.]
Err ever on the side that's safe, And when in doubt, abstain.
[1884 G. Weatherly ‘Little Folks’ Proverb Painting Book 64]
When in doubt, do nowt. This shows the cautious Cheshireman at his best.
[1917 J. C. Bridge Cheshire Proverbs 155]
I don't know. I think it's one of those occasions where it's best to follow the maxim: When in doubt, don't.
[1952 H. Cecil Ways & Means ii.]
‘When in doubt say nowt’ is a precept enshrined over most magistrates' courts.
[1972 E. Grierson Confessions of Country Magistrate vii.]
What to do?‥‘When in doubt, do nowt,’ had always been my grandfather's advice.
[1981 E. Agry Assault Force i.]
Related to: action and inaction; decision and indecision
Bibliography of major proverb collections and works cited from modern editions is available here.
