Green’s Dictionary of Slang

bos-ken n.

also bosken
[Lat. bos, ox + ken n.1 (1)]

a farm house.

[UK]Hotten Dict. of Modern Sl. etc.
[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor I 424/1: Up at a bosken (farm-house) they’ll get among the servant girls.
[UK]Sl. Dict.