Immigrants living in camper van(s)

A large camper van has been parked up under the trees all Summer. All windows are obscured but we know it is permanently occupied by 1 and some times more eastern Europeans. They keep a very low profile, but bottles of urine have been found nearby. Yesturday another large and much newer camper van parked up next to the first one. This too is occupied (we see the air vents in the roof being opened and closed), but we have yet to see the inhabitant(s). Residents of Laburnum Close have tolerated the first camper van so far, against their better judgement but, now with the arrival of another camper van it is time to take action.