Green’s Dictionary of Slang

(UK/US black) a woman.

[1934		J. Peterkin Roll, Jordan, Roll 171: Now he is old and poor, with no decent liquor to drink, and only one ‘scold gully’ woman too old and too fat to work].
1997		C. Newland Scholar 22: You lot see the gullies at my yard innit?
2001		Source Aug. 124: I’m straight gully, y’all! Motown done got gully, and they pick the grimiest of all to be their first lady!
2002		‘Touré’ Portable Promised Land (ms.) 156: We Words (My Favorite Things) [...] Celly. Salty. Polly. Gully.