It's easy to be cynical about Twitter but there are times when it comes into its own. Last week's NS exposé of the News of the World phone-hacking scandal, written by an up-and-coming cub reporter named Hugh Grant, has had an extraordinary afterlife on the site. "Magnificent," Stephen Fry told his 2.5 million followers. "Amazing," said the singer Lily Allen to her 2.8 million fans. Within hours, there were thousands of retweets, including a grudging one from Piers Morgan (a former NoW editor). The story has now gone round the world, putting renewed pressure on the Met, which is investigating the hacking case. It has even made Mr Cameron - who is very friendly with the Murdoch press - look a bit of a twit . . .