I think this commonly held mistaken belief comes about from a court case about 20-odd years ago when somebody appealed it all the way to the House of Lords. He'd been done for jumping a set of temporary lights and argued that, as the lights didn't have horizontal black and white banding on the pole, that they weren't proper legal traffic lights and that he was justified in ignoring them. Our judges, in the way that they have of ignoring any common sense, upheld his appeal.
But the law was put right pretty damn quickly afterwards. They're legal now,
Dean, let me know next time you're on a site where you'll be doing that stunt, I'd love to watch.