A figure of blame. If something has gone wrong, it invariably is John Kett's fault.
A John Kett can also be someone who enjoys drinking normal drinks, but whilst on fire. See - Flaming pint.
I can't believe the Conservatives are reducing Child Allowance - I know, I blame John Kett.
"My God! That man's pint of lager is on fire!"
"I know, he's doing a John Kett."