It's been known widely for some time that on every British nuclear-armed sub, there's a safe, and in that safe another safe, and in that second safe a note from the Prime Minister commanding the sub on what to do in the event that the motherland should be wiped out in an attack while they were away.<p>That would mean it is impossible that they need some sort of special code, as if they did, that code would have to be accessible to them already, and then what is the point?