London has today been saved from a grave threat to our national health and security. Perfectly coiffed, saccharine sweet, endlessly talented Martha Stewart has been denied a visa to visit the UK. There are apparently quite a few out there who still venerate this triumph of PR over commonsense. Empress of daytime TV with a terrifyingly large business network, she is as firmly ensconced in American popular culture as Delia is over here. But insipidity......