I'm travelling soon and one of my young friends told me that he had to take off his jeans and only remain in underwear last week in London Heathrow when departing for a flight because there was some metallic piece that kept on setting of the detector. They asked him to take of his jacket, empty his pockets until they decided he had to take them off.
Now, I'm not sure whether he's exaggerating or not but I am concerned about this. It doesn't seem that they offered him to be screened in a private room and just in public.
Is this legal or illegal?