First, you need signs to say that the road is private. Then you need signs (may be on the same sign) to warn of clamping. If you employ a car clamping company, their terrorists must be licensed by the Security Industry Authority. The licence is in the form of a badge and must be displayed so that the name and photograph can be seen. The licence costs around �200 for each person, so there are a lot of people doing this unlicensed. For a number of reasons, it is not worth getting involved with unlicensed operators.