Indeed these razor blades (rather than the razor itself) are not allowed, nor are barbers' style "cut throat" razor. These are the two types which are banned in the UK, elsewhere in Europe and most of the world as far as I can tell. Other commercial razors are allowed. I travel HBO with several of the household name consumer disposable razors as well as - on other occasions - razors similar to Fusion with replacement blade packs, and no matter where I've been globally, they have never even attracted attention from security. If, for whatever reason I was in LHR or LGW (same pack is given out there) and razorless, I think I'd go scruffy until I could get a better item, the ones supplied are not much better than the Bic style razors of the 1970s. Luckily Boots is able to supply vastly better devices, which will last for at least a few weeks, for a modest fee.