From British Circus and Fairground Lingo; Carnival Slang; palone/polone - not listed

From Wikipedia; Polari palone woman (Italian paglione – "straw mattress"; cf. old Cant hay-bag – "woman");
also spelled "polony" in Graham Greene's 1938 novel Brighton Rock
Once again, I can imagine MacColl reading Graham Greene, but not many lorry drivers.

But here's an example of usage in print from 1949, the year Champion at Keeping Them Rolling was written;
charver, n. A sexual embrace: theatrical (orig. Parlyaree): late C.19–20.—2.
Hence, a girl, a woman, esp. as sexual partner: market-traders’: late C.19–20. (M.T.)
Also spelt charva, as in bona palone for a charva, a good-time girl. (John o’ London’s Weekly, 4 Feb. 1949.)
From A Dictionary of Slang and Unconventional English 8th Ed. / Partridge, Eric; Beale, Paul.