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You all make valid points guys, I don't really think they could pin wasting police time on a person for doing that however as I reckon you could probably have them for harrassment, hadn't considered fraud though, unless I just admitted it to be icing sugar straight away if they nicked me, mind you I know of folk being approached to buy weed off people in the street and been sold nettles, happened to a relative last year so it's quite good to know that there are laws protecting against that sort of stuff.