Photograph found on the amazon.fr website (and available in English)
On the right side, you can see a stamp issued in France in June 2006, one of the six members of the Personnages célèbres annual serie about about Mozart's operas. Each stamp reproduced a costume's design found in the archives of the French National Library (Bibliothèque nationale de France). The costumes were put in front of a golden background by stamp designer Valérie Besser. The Mr. Bean's book used a character from The Abduction from the Seraglio.
The book is the holidays diary of comic character Mr. Bean, played by British actor Rowan Atkinson (watch him in the TV series The Blackadder, it's better I think). Bean tried to discover France and sent some post cards franked with another 2006 French stamp : "Antibes - Juan-les-Pins", designed and engraved by Pierre Albuisson.
Phil@poste (responsible for the French stamp designs and selling) must have authorized the reproduction of these stamps. They were not chosen by chance : Albuisson's one won the Grand Prix de l'Art philatélique (Main French philatelic art prize) in November 2006.