Green’s Dictionary of Slang

(UK Und.) to unlock.

1812

Vaux Vocab. of the Flash Lang. in McLachlan (1964) 277: unslour to unlock, unfasten, or unbutton. [...] Speaking of a person whose coat is buttoned, so as to obstruct the access to his pockets, the knucks will say to each other, the cove is slour’d up, we must unslour him to get at his kickseys.