Green’s Dictionary of Slang

stupid, foolish, ‘soft’.

c.1857		J. Lawrence in Gilmour The Ruling Caste (2005) 21: He forbade his officers from going up in the hills for the hot weather and made known his disapproval of ‘a cakey man’ by which he meant someone [...] pretended to much elegance and refinement.
1888		S.O. Addy Sheffield Gloss. 35: Caky, silly.
1889–90		Barrère & Leland Dict. of Sl., Jargon and Cant.
1896		G.F. Northall Warwickshire Word-Book 41: Cakey. Weak of intellect; silly.
1915		M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 213: cakey, foolish; below par. ‘This composition sounds cakey’.
1933		M. Marshall Tramp-Royal on the Toby 98: It wasn’t long before I was completely cakey, doolally.
1946		R. Grinstead They Dug a Hole 54: Why should they tell us a cakey bar like that if we’re in the Med?
2001		K. Sampson Outlaws (ms.) 90: Paul told us it stands for Young Men’s Cock. Which is a bit cake, to be fair.