Although I tend to agree that your photo probably was the source, I'd have to say in my (admittedly uninformed) reading of U.S. "fair use" policy, that they're also in the right. As long as they substantively changed the work, and are not reprinting it as a photograph but as a pure drawn silhouette (no matter how slavish the drawing) it would be considered a transmutive work.
Every dang art student in grade or middle school has 'copied' at least one 'photo' in their classroom - reproduction of what you see is one of the first steps in any art learning, even before you try to do it from an actual 3D model (or still life). The fact that its not for financial gain has little to do with it. Was Warhol's drawing of a Campbell's soup can plagarism? He was clearly reproducing Campbell's logo, label style, etc but in a different format. Only the tool in this case (the use of a computer vs silkscreen process) is really different.
Although I usually hate Wikipedia being brought out as any sort of exhaustive reference, the section here on fair use seems informative, to this layman's eye. http://en.wikipedia.org/wiki/Fair_use
The use of a drawn silhouette on a T-shirt doesn't 100% mimic the photo, doesn't "diminish the market for the photo" (as it would if they simply photoshopped it to remove a © marking but otherwise left it substantially and clearly a "photo" on a t-shirt), etc.
Gray area, for sure. Seems to me by changing their design they're acting out of an interest to be completely fair to you and avoid conflict...not admitting "guilt".
Of course all my random blathering applies to U.S. law and my (mis?) understanding thereof. Perhaps U.K. law is totally different?
p.s. no insult to your photo at all, I like it, but I have to admit I like their new
Edited by rtrski, 05 February 2009 - 02:11 PM.