My teacher wasn't half as nice as yours seems to be

"My teacher wasn't half as nice as yours seems to be.
His name was Mister Unsworth and he taught us history.
And when you didn't know a date he'd get you by the ear
And start to twist while you sat there quite paralysed with fear.
He'd twist and twist and twist your ear and twist it more and more.
Until at last the ear came off and landed on the floor.
Our class was full of one-eared boys. I'm certain there were eight.
Who'd had them twisted off because they didn't know a date.
So let us now praise teachers who today are all so fine
And yours in particular is totally divine."