Green’s Dictionary of Slang

one who can sense the right answer even when they have no facts or expertise on which to base their opinion.

1978		J. Gash Gold from Gemini n.p.: Divvie? Maybe from the old word ‘diviner’, as in water. [...] It’s slang for anybody who can guess right about a thing without actually knowing.
1999		K. Sampson Powder 108: He’s a little grammar-school divvie from Eccles.