NOTE: this is the ONLY time Hergé signed by using his first name (Georges) instead of using the other monikers he used to sign his books (Tintin at first, Hergé later)

The boook, along with a similarly signed EO of its prequel Le Testament de M. Pump (1951) were dedicated to a couple of VERY CLOSE friends of Hergé and his first wife. Edouard et Manou Cnapelinckx designed the "Foulard de La liberté" for Hergé when Belgium was rid of the Germans at the end of WW 2. They can be seen, along with Hergé and a few other friends, in the famous scene of the royal palace of King Ottokar, in King Ottokar's Scepter.

It would be impossible to evaluate the price of the two books.