Green’s Dictionary of Slang

niggler n.1

also nigler
[niggle v.]

a promiscuous man or woman.

[UK]R. Brome Jovial Crew II i: Heart and a cup of Sack, do we look like old Beggar-niglers?
[UK]Greene & Lodge Lady Alimony II v: Ha, ha, ha. This was a bold-fac’d Nigler.