Political correctness has crippled the left's sense of humour.It's a dangerous business, writing humour. Literally, in some places, the ruling brutocrats will have you swinging by your thumbs for the mildest of knock-knock jokes at their expense. Figuratively, in others, where hecklers, critics and hungry defamation lawyers are waiting to pounce. I guess it's not surprising that so many stand-ups are bipolar. What is surprising is just how successfully the new right, for want of a better tar brush, has been at colonising this outpost of public discourse. If you're looking for a year zero from which to trace this...