The criminal justice bill gave them the right to stop & search ANYBODY, and it gives them enough scope to find WHATEVER reason they see fit to come up with. It was meant to be for suspected drug dealers, terrorists etc, but it can be used on anybody.
A bit of advice to anybody who gets stopped reguarly, each time you get stopped or searched, ask them for a search record. They have to give you one if you ask for it by law, but they don't like telling you that. Keep the records in the van, because if they stop you more than 3 times in a month or so, and get nothing on you it's harrasment