Ok , um, I'm a 4th year law student...Here are some basic ideas to work with...
- In order to be done for 'possession', you must be in physical possession. Possession in this sense means quite literally that. If you don't pick your wallet up, you cannot be done for anything at all...you are in possession of nothing illicit. To give another example...if you had a bag of weed, and threw it in somebody's house cos u were paranoid, then the cops came...you could not be done for it as it was not in your possession (you have 'abandoned' it) and your house owner could not be done as while it was arguably in his 'possession' (ie, in his house) he had no knowledge of it whatsoever.
To reiterate: Not in your physical possession, no actus reus, no crime. No knowledge of it, no mens rea, no crime (unless possession only requires the actus reus and absence of fault acts as the defence...feel free to correct me on this lawyers) but yeh...follow my advice above and you can't go wrong