Carrying Coal to Newcastle

You're no doubt familiar with the saying "carrying coal to Newcastle." Since Newcastle, England was a coal mining center, the saying clearly arose to indicate uselessly unnecessary work.

I was recently watching one of those endless British murder mysteries so often found on Masterpiece Mysteries (Poirot, Miss Marple, etc.) and in one scene, a lady uses a watering can to water some outdoor potted plants.

Talk about carrying coals to Newcastle: watering plants in soaking wet England seems to be one of the most redundant things imaginable. I would think draining potted plants would be quite a bit higher on the list, given England's delightfully moist climate.

But, there's your touch of the dramatic for the show.