Green’s Dictionary of Slang

deeache n.

the head.

1907		D. Stewart Wild Tribes of London in Illus. Police News 28 Dec. 12/3: ‘Harry copped him on the D.H. (head) with a shovel!’.
1910		D. Stewart Tragedy of the White House in Illus. Police News 20 Aug. 12/4: ‘He knocked her on the D.H. (head) and made a bloomer (misake) of the job’.
2001		J. Burkardt ‘Back Sl.’ Wordplay 🌐 deeache: head.