While watching the eponymous documentary on Stephen Hawking, his wife described her husband's behaviour when he was deep in thought. She said he could be surrounded by children and not even notice what was going on. She then said, "It used to drive me spare."
I got the gist that she meant it drove her perhaps crazy or to despair. Is this a British idiom? If so, how did it originate? Was there an omission in the phrase?
How does one get to spare from annoyed/upset?
I think that while the previous post is somewhat plausible, it is rather tenuous. To go spare (becoming unemployed) and being driven spare (getting angry) seems quite a leap to me.
To me, even extreme anger and being distraught are two entirely different emotions. The link to loss of employment appears speculative in my mind.