Somewhat belatedly I'll chime in with astonishment at the seeming lack of gobal utilisation of this phrase! Must be a Brit Commonwealth thing by the looks of those of us that know it.

I see it inhabiting the same basket as the recently discussed "run of the mill" in that it's a manufacturing / production term.

Not to be confused with "one of" - normally present on a parts list (and written "1X" in a table on the production drawing) to indicate that the finished item only requires one of a particular component. (Just to confuse things, the production drawing for a "one off" product would no doubt have a few "one of" items on the parts list!)

Now, don't tell me you don't use the phrase "one of"?

stales