When i was a local councilor , our local police woman came along to a meeting to ask for £10k towards the cost of smart water for around 1/4 of the village households .
Not a big request , but when she explained that the police were going to be going around the carboot sales checking for smart water marked items for sale .And that any one found selling marked items could be taken into custody till the results came back to prove if the marked item is not stolen - We refused the police the money .
So just a thought - if your on your way back from a show with your prized and marked possesions in the back of a van , and are pulled over for a " routine check " by a policeman with a dragon light ( UV lamp ) .I suspect that you could be held without charge till the results come back , could be a long weekend in the nick especially if your just heading off on a bank holiday weekend - lol ...