These are the aristocrats and gentlemen (this is a patriarchal age, let it be remembered) who exercise total power over the British Royal Navy, including its Marine component. They are usually seven in number. Their chair is the Lord High Admiral. They are, of course, still subject to the monarch, and thus, from the British standpoint, a woman may still rule the waves as Britannia incarnate. This is an onerous and responsible post, not a sinecure, and these gentlemen respond poorly to any speech not prefaced by "My Lords".
NB The title is the correct one, not 'Lord Commissioners'.