There was a very significant development last week in the case of Paul Chambers, whose ill-conceived joke on Twitter about blowing up an airport resulted in a criminal investigation, an arrest, a charge, and a decision to prosecute by the Crown Prosecution Service.

Mr Chambers has now switched his plea to Not Guilty, thus forcing the CPS to prove that he has committed an offence.

By way of background, you may recall Mr Chambers pleaded Guilty at Doncaster Magistrates Court last month.