Green’s Dictionary of Slang

boman adj.

(UK Und.) safe.

[UK]A. Smith Lives of Most Notorious Highway-men, etc. (1926) 207: [...] There’s a cull knows us, if we don’t picque he’ll bone us, i.e., that fellow sees us, if we don’t scout off, he’ll apprehend us. Ding him, i.e., knock him down. Then we’ll picque, ’tis all boman, i.e., We’ll be gone, all is well, the coast is clear.
[UK]New Canting Dict. n.p.: Then we’ll pike, ’tis all Bowman; We’ll be gone, all’s well, the Coast is clear.
[UK]Bailey Universal Etym. Eng. Dict. [as cit. 1725].
[UK]Whole Art of Thieving n.p.: All’s bowman all is safe.