Green’s Dictionary of Slang

climber n.

[climb n.1 ]

(UK/US Und.) a cat burglar.

Emporia Dly Repub. (KS) 28 Apr. 3/2: A thief who robs houses in the early evening is called [...] ‘climber’.
[US]Flynt & Walton Powers That Prey 64: I say that we hunt up a good sneak an’ climber (sneak-thief and burglar).
[UK]J. Morton Lowspeak 39: Climber – a burglar who literally climbs up the outside of buildings, particularly hotels. There is now said to be only one working in London.