Sheppey-----well done you win the pedantic award of the day, yes it was to make sure plugs weren't fouled up and you, more importantly, had power available when you needed it. I guess the term "warming the Engine" is a little misleading but that's what they simply called it back then.
Either way it should be done during a glide.........before it gets too low.....
So, my point still stands......sarcastic tone or not.
Didn't learn ab-initio on Cessnas mate, sorry to disappoint, I guess you had a 50/50 chance!!