Re: Only cracking I have done is
"What I want to know is how they worked that out as opposed to just picking a basic lock."
Two obvious ways:
1) You can save a good deal of money by purchasing filing cabinets without locks, but with the capability for locking hardware to be installed. As you install it yourself, you note that the locking bar is held in place by gravity, not by the lock itself. The lock only prevents a lever from moving, and thus moving the the locking bar. The bar itself is free to move if you tip the cabinet.
2) You are the poor bastard selected by the Boss to move filing cabinets from one office to another. Naturally, the Boss insists that they be moved fully loaded, and locks the drawers "so they don't shift on you". Inevitably, one of the cabinets is top-heavy & manages to discover it's center of gravity at an inopportune moment. As it hits the ground, one or all of the "locked" drawers pop open.