Hot on the heels of a man being charged for tweeting "Crap! Robin Hood airport is closed. You've got a week and a bit to get your shit together, otherwise I'm blowing the airport sky high!!" someone barely out of their teens has now been hauled in front of a magistrate for joking about child abduction and if the BBC are to be believed (about this, if not the conduct of Jimmy Savile) "[about] 50 people went to his home address and the defendant was arrested on Saturday night at a separate address for his own safety."
Americans probably aren't wrong to suggest that criminalising hate speech is the thin end of a wedge. It took massive campaigning and publicity to amend a recent piece of legislation that had crept in scope to chill criticism and ridicule of invisible sky wizards, with the revised version conforming more to the traditions of British law; i.e. that there has to be demonstrated intent to incite hatred and violence.
That's what's missing from the earlier UK Communications Act 2003, which includes "(1) A person is guilty of an offence if he (a) sends by means of a public electronic communications network a message or other matter that is grossly offensive" and has provision for custodial sentences.
It's one thing if a person was trolling friends or family with jokes or comments. What appears to have happened in this case is that someone didn't like what had been repeated by someone else in a Facebook status and decided to recruit a lynch mob by spreading it around.
Irrespective of legal semantics, whether society needs gallows humour and whether Matthew Wood would have been any safer had he changed the punchline to "Santa only comes in December" and required readers to work out the rest in order to be offended, there's particular danger in legal test cases being formed from cases that provoke hysteria. A nation pissed off about planes being grounded by unprecedented bad weather has sympathy with someone who's obviously not a threat joking about it. A nation still waiting to find out whether April Jones was killed and/or molested by Mark Bridger is less likely have much sympathy with someone joking about it. On a sliding scale it's probably more sympathetic than Frankie Boyle or Russell Brand being able to use broadcast media as a platform for bad-taste comedy, but whether popular opinion finds a remark funny or offensive shouldn't be the measure of whether it's legal to say it. Because there's dark and tasteless humour around every Myra Hindley or Fred West... it just happens that arresting people who say things on Twitter and Facebook is a self-perpetuating cycle and currently flavour of the month with both media and the police, and increasingly more legislation is in place to give the option of arrest for something. Even the Clash song is out of date... it may harm your defence if you do not mention when questioned something which you later rely on in court.
There are also occasional positives to media and mob pressure (often called the Streisand Effect online) such as the reinstatement of a blog that was reviewing school meals and raising money for charity. But on the whole it's how unpopular voices are treated, including dickheads and bigots that aren't calling for violence, that measure a society. And maybe next time it's something someone you know said on Facebook that gets spread and leads to intimidation and charges.