Why are transistors called "Q"?

[John Honniball]

Here's a question that came up at the office when a colleague looked
at a PCB and asked "why are the transistors labelled with Q?"  Well,
I suggested it might be to avoid a clash with "T" for transformer.
Or maybe "Q" represents a generic semiconductor, such as a FET, SCR
or triac.  Or is there some other reason?

-- 
John Honniball
coredump at gifford.co.uk