Oh.
That’s where it’s from.
No one in the US knows that.
And, whomever has ever seen that show ought to be censured. :)
One of the funniest Brit comedies that used to be shown here. I supposed it’s not P/C anymore.
Too bad.
Oh....There are a lot of elevator scenes in that series.
It Way predates that British show to the beginning of television; and Most people from then recognize it.
Wrong.
I think it is an 'old' joke from the days when elevators had human operators who would announce the floors rather than 'do it yourself' push buttons. The British professor is old - so that would make sense.