Green’s Dictionary of Slang

a prostitute; thus thrummy adj.

1723		C. Walker Authentick Memoirs of Sally Salisbury 97: That proud Minx you seem to have such a Liking to [...] is little better by Extraction, than any of our Two Penny Thrums.
1768		A. Ross ‘The Rock & the Wee Pickle Tow’ Helenore in Wattie Scot. Works (1938) 143: I’m as warm and as bra’, / As thrummy-tail’d Meg that’s a spinner o’t.