Hi all

From an article about prince Charles:
He​ has an enormous private staff— secretaries, deputy secretaries, press officers, four valets, two butlers, housekeepers, two chefs, two chauffeurs, ten gardeners, an army of porters, handymen, cleaners and maids. They are expected to get everything right. When HRH (His Royal Highness) feels they have performed their duties well, they are praised in a royal memo.

What does "praised in a royal memo" mean? "I do know that "memo" means "memorandum" - a written message. So,what does he do exactly when he "praise in a royal memo"? I can hardly imagine him just writing down something good about these people on a sheet of paper:)