(http://en.wikipedia.org/wiki/Today_(BBC_Radio_4)#Notable_fea...)

> Journalist and historian Peter Hennessy has made an assertion, in one of his books, that a test that the commander of a British nuclear-missile submarine must use to determine whether the UK has been the target of a nuclear attack (in which case he has sealed orders which may authorise him to fire his nuclear missiles in retaliation), is to listen for the presence of Today on Radio 4's frequencies.