I'm sure there are others but P&O's Oceana and Artemis certainly do, although they don't do the same journey throughout the winter season as quite a few of their cruises are Caribbean only.
I am just wondering why you would only want a £ ship if you don't mind me asking?
Maybe there's a £ shop on board, Silly!!
Not for the pound shop Wilba, it's becos the $ to £ has nosedived and if everything on board is in dollars then the ship might "add" on the conversion rate to compensate for the down turn in bookings etc.
P&O's Oceana definetley uses GBP's. I'm booked on it for next November leaving Acapulco and ending
up in Barbados via the Panama Canal. All P&O ships are GBP's.