The answer, in my piece today on Beacon: neither have their rules written down, which makes them flexible. The British constitution is whatever Parliament decides it to be; and the rules on ridicule have become basically that you can make fun of people based on what they choose to do, not what they were born as.
That means making fun of someone on Fox News over what he chooses to say about Birmingham is absolutely fine, as is Boris Johnson saying this:
If you look at all the psychological profiling about bombers, they typically will look at porn. They are literally wankers. Severe onanists… They are not making it with girls and so they turn to other forms of spiritual comfort – which of course is no comfort.