An interesting little story for you.
As i'm sure some of you are aware, there were quite a few chemicals available on ebay relating to pyro hobbies in the past year or so, but recently they've all dissappeared.
Well, a friend of mine (a respectable young guy - he's a student who just likes to build fireworks, rockets and mess around a bit, like we all do to some extent) bought some KNO3, S, Amonium nitrate and cardboard tubes etc from some German guy on ebay who had his own little shop selling chemicals. Now, he didn't buy huge quantities of stuff, but i suspect that the 1kg of Ammonium nitrate was what really caught the authorities eye.
Anyway, this purchase was a one off and it was made in 2003. At some point afterwards the German guy got raided, and my friends details were found along with many others. Interpol got in touch with the UK police and he was arrested on anti-terrorism charges. The police held him for just under a day, while they searched his flat.
They found the chemicals because he has not used much of them, and they found tubes and mixing apparatus and other bits and bobs. They also imaged the HDD on his PC.
They were very nice to him, he wasn't locked in a cell, and they openly said almost immediately they they thought he wasn't a terrorist but they were just "going through the motions". So, he had his chemicals confiscatated, but was released without charge or a caution, and was just told to be more sensible in the future. The only questions he has is whether they're going to persue the fact he has ?1000's of illegal software on his PC
Anyway, it's an interesting tale. On the one hand you wouldn't think the police would come after you for an ebay purchase made years ago, but then on the other hand they were very nice to him and obviously take a very leniant view to the making of homemade fireworks and suchlike, providing there is no malicious intent.
So, just bear these thoughts in mind if your buying chemicals from dubious sources in the future.