1. At the outset someone who is visiting the houses is not a resident and therefore is not entitled to park in a permit space for residents. Accordingly, you should simply call a traffic warden and ensure that this person receives a ticket. Just because this person is some neighbour's friend does not allow him to flout the law. Additionally, the law gives a landowner a private right to clamp trespassers who are trespassing on their land. Accordingly, you should ascertain what house or houses does this off street parking go with and if you have the legal right of ownership, you can clamp this person's car yourself. However, in order to do this, you need to put up a notice that non residents parking there will have their cars clamped in order that it be lawful. So your first step is to ascertain who owns the land on which the parking spaces exist. Be aware that even if the land is owned by a third party, there may be an easement of parking, or a lawful right only for residents to park there. In such circumstances, the car of any trespasser occupying the parking space may also be clamped. So check who owns the land and what is the legal basis of the parking there.
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