Green’s Dictionary of Slang

nethersken n.

[SE nether, used in names of places to mean lower, low + ken n.1 (1)]

a cheap lodging house, frequented by beggars, criminals and the very poor.

[UK]W. Newton Secrets of Tramp Life Revealed 12: You will be directed to the lodging-house or ‘Nether’s Ken,’ where he will have a woman in readiness.