This is a bit off topic, mods feel free to remove. May be something a few people here could possibly be affected by though. Seems like nasty, sneaky behaviour by a charity though. They surely can't have missed the controversy over Microsoft's attempted copyright grab for stock images, harversting photos from the unwary to sell on and squeezing those trying to make a living.
http://copyrightaction.com/forum/national-trust-picture-yourself-competition