I’m not 100% sure of the legalities surrounding the use of radar detectors in the UK, but I think that currently they are legit. In the US, they’re pretty commonplace and, like speed camera locators on GPSs, are sold under the guise of promoting safety and only one state has banned their use entirely.
Beltronics currently has a selection of some of the most advanced kit available on show at CES, including the unfortunately named STi Driver. This new gizmo not only protects against X, K and Ka band radar and Laser; it is also completely invisible to new Radar Detector Detectors (RDD) that are starting to crop up in those regions where they are illegal. And with the UK law still in an uncertain place, that might someday prove itself to be an extremely handy feature.
The Beltronics spokesperson I chatted with, who regularly adopted a very theatrical hushed voice, explained that the technology remains hidden to those grassing RDDs by completely eliminating leaked signals form the osciallator.
Unfortunately I can’t find any indication of a UK launch, but Beltronics do sell over here and there’s also the possibility of importing.