I can't comment on the legality but I fitted HID conversion to my last car (vw passat) without the conversion it was lethal & with the conversion I could actually see where I was going. I never got flashed and had 3 MOTs from different stations with never a comment. It seems to me all the legality quotes relate back to a 2006 dft 'opinion' which never seems to have been followed up in any meaningful way. My personal experience is my ability to drive at night was transformed and no one ever brought any problem to my attention. It doesn't seem like the crime of the century to me.