What is the origin & meaning of "It used to drive me spare"? [duplicate]

Solution 1:

An older form of this expression, go spare, meaning "become angry" has been discussed on ELU; links there suggest that spare in that phrase may derive from a) "excessively (angry) or b) the emotional reaction to being made "spare", i.e. unemployed.

MORE:
Partridge, *A Dictionary of Slang and Unconventional English) gives this:

Note that second definition. In the Journal of the Royal Army Veterinary Corps for 1948 I find this:

... all a muleteer had to do before going into action or taking cover was to pull, as it were, the alarm chain, let his mule or pony go spare, still retaining a reasonable assurance of the latter being found …

It's beginning to look like "go spare", with a root sense of being unused (as in having some cash or other resources "going spare") or idle (as in being unemployed) or allowed to move freely (as in the RAVC use), evolved in the WWII British Army into an active sense of going out of control (Partridge, Definition 3).

In Blackwood's for 1964 I find this:

... a runaway horse with a vehicle going spare behind it is a lethal combination ...

That seems to me to unite the "unauthorized leave" and "out of control" senses.