Been watching an Kiwi series from 2005,
Seven Periods With Mr Gormsby.
When a boys school with a poor reputation has to resort to rehiring an notoriously "old school" educator, lessons are learned on all sides ahem.
Lasted only one more series.
The lead is fun, a sort of blend of Terry-Thomas and R Lee Emery
. The trick here is that he isn't the worst character in the show, though his language would have the sensitive ones a-tweeting en masse now. It's on the YT, so see for yourselves ahem.