he found he could silently slip in and out unnoticed by pushing his unsophisticated old ID card through a gap between the Yale lock and the door frame
I worked in an office where it was generally quicker to open the front door with a credit card rather than the key. The Yale lock was only used at lunchtimes when the front office wasn't always manned (overnight there was a deadbolt) but still not very secure.
Biting the hand that feeds IT
