Maid Marian, n. — Green’s Dictionary of Slang

Maid Marian n.

[the morris dancing tradition of having that character played by a local prostitute]

a prostitute.

[1589		Nashe Pasquil’s Returne in Works I (1883–4) 97: Martin himself is the Mayd-marian, trimlie drest vppe in a cast gowne].
c.1597		Shakespeare Henry IV Pt 1 III iii: This house is turned bawdy-house [...] And for womanhood, Maid Marian may be the deputy’s wife of the ward to thee.