Copyright question

[covboy]

A bit of a random thought on a (very) hypothetical question. You take some shots at a site/venue that specifically states that all photography is for personal use only. You later enter a shot into a competition where the organisers claim use for all entries (for whatever purpose) and it wins ! Competition organisers then use photo for advertising purposes. Would the owners of the orginal venue have to go after the final user. ( I assume by enteriing a competition like this you hand over all rights to the photo ?)

(I've too much time on my hands at the moment )