Some great info over on RWI regarding customs in the UK, and what measures to take. There are clear talks of if you get a letter from above said company, where they mention destroying your property, all you need to do is write to them telling them you do not approve this, and the watch will be forwarded onto you.
Obviously this is open to disprove, but the thread below is a long one with several pages of members who have all experienced customs issues in the UK.
Here's the thread. It's actually a poll, which is quite revealing on it's own..
http://www.replica-watch.info/vb/showthread.php/uk-customs-seizures-113838.html?highlight=seized