Further to my comments above
(made quite some time ago now!), this video clip of Hergé and Warhol meeting in Brussels
, to be found on the RTBF (Belgian state broadcaster) website, offers visual evidence to the effect that there are at least
four, rather than three, prints in the edition.Update:
Yes, having found other sources for the information, it's definitely four pictures in the series.
Perhaps more importantly, I should mention here that the original photograph used by Warhol for the portrait was by Jean-Pol Stercq, who worked for Le Lombard, and who took it upon himself, as part of a personal project, to get portraits of the artists who worked on Tintin
To be fair to Warhol, he may have used the picture in good faith, the photo being selected by Hergé, but however the decison was made, or whoever was responsible, according to an article by Stéphane Steeman, nobody asked Stercq, who was not compensated in any way.
However, after thirty years, Stercq reestablished his rights in the picture, and now gets a credit and royalty when any of the Hergé series of portraits is reproduced.
I think that this also might call into question the story I mentioned above
, that Hergé was surprised to keep recieveing pictures, and that the worry was that Warhol would keep sending them, might have to be relegated to the ranks of "a good yarn, but not very likely", as the indication is that Warhol exhibited the four pictures at Gallery D in Brussels, and that Hergé purchased three for the sum of BF2,000,000. The fourth was bought by a private individual.