This happened in the same train trips as in this.
Me and my friend Duche were walking in Exeter as there were lots of people milling around.We went to investigate and walked down this road where people were going towards. Then Duche says "Pulle! pulle". I knew that means, the slang term for the police. So there this policeman was walking towards us on the other side of the road. Without says anything he motioned me to cross the road. He went straight to the guy and said in his best French acsent " Where is the skul road?". The man said there is no school road but there is a school lane. Viola says Duche and we proceeded.
The moral of the story is: if you are carrying illegal substances, which we did, best to go to the police-person rather than wait for them to come to you. Well atleast it worked at that time init?