We have wrenches, and monkey-wrenches or pipe wrenches. We also distinguish them as box-end or ring-end wrenches, or adjustable wrenches or F-head wrenches.

But around these parts the colloquialism has been dumber than a box of hammers or a box of rocks.

If we said "dumber than a box of spanners" someone would think we were castigating the abusers of e-mail.

A