Poached Brill with Potato, Celery, Bacon and Marjoram

A bit of a treat this one, best saved for when you are out to impress someone, or for that romantic dinner for two. The sauce is quite rich, as is evident from the amount of cream, but it is sheer elegance. If marjoram is unavailable then oregano, which is almost identical, will do. If neither is available then thyme is a good substitute, but as with all herbs only use it when fresh.