Scapa Flow, v. — Green’s Dictionary of Slang

Scapa Flow v.

[rhy. sl.; ult. British naval anchorage in the Orkney Islands used in both WWI and WWII]

to go, esp. to run off.

a.1945		L. Payne private coll. n.p.: Go. Scapa Flow.
1958		(con. 1940s) B. Behan Borstal Boy 367: Out you lot, Scapa Flow.
1969		S.T. Kendall Up the Frog 13: ’E wraps the Lilian Gish in some linen draper an orf I scapa flow.
1971		J. Jones Rhy. Cockney Sl.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.