Green’s Dictionary of Slang

a police officer.

1935		A.J. Pollock Und. Speaks.
1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1960		J. Franklyn Dict. of Rhy. Sl.
1972		E. Grogan Ringolevio 203: He was given a sound thumping by the spinning-top cop.
1999		R. Walton ‘Cockney Jack’ 🌐 ‘What’s going on here?’ asked a husky voice. Jack turned around to see a spinning top walk up.