[Phil G4SPZ]

Very interesting, Dave. I have known Bakelite pendant lampholders start to smell of fish when they degrade, but that is after thousands of hours exposed to the rising heat from a 100 Watt light bulb!

As you say, you'll probably never know what caused the fault, but the important thing is that you found the cause! Perhaps it will be best to put that particular Avo on display with a discreet label saying "do not use 1,200 volt range"...