You kindly advised me on the purchase of a Mercedes SLK 200 and its acquisition has, inevitably, brought a desire to go off for long drives, which previously my husband and I have generally not done. We have never thought the ownership of a sat nav to be worthwhile. However for a recent weekend and to simplify negotiation of the myriad roundabouts in Swindon, we borrowed a sat nav and were surprised to note it gave warning of the location of, so-called, "safety" cameras. As I understand the system, the sat nav is programmed with the location of these cameras and needs to be updated periodically, not only for changes to roads but also with fresh locations of cameras. This means there is an inevitable lag between the siting of a new camera and the sat nav being updated. My research has identified the availability of radar detection systems for in-car use. These claim to be able to detect the radar emissions from "safety" cameras and other radar-emitting devices used for speed detection, such as those used on motorways. Because this system works in real time, and is not based on retrospective data, like sat navs, it should be more effective because "safety" cameras can be installed or moved, which the sat nav is unaware of until the next periodic update. Are these devices legal in the UK and do they do what they claim?