Not in any areas of the north I've lived / stayed in. the only people in England who call pants 'underpants' and trousers as 'pants' are those who watch excessive amounts of US TV shows.

I'm from Salford and use pants/trousers interchangeably, have done since I was young. Perhaps this is also due to watching films too, which are mostly from the US over here. I haven't watched that many US programmes in my life time. I don't watch much TV at all really!

As a side note, I saw undies in the original too!

Never heard that in Yorkshire. Possibly a more localised thing?

not in my experience of scotland, though i do know geordies and irish who say pants.