Myth exposed: how many crimes in London are really carried out by foreigners?

The Daily Mail and Daily Telegraph would have us believe that one in five of London’s crimes are committed by foreigners. However, the Five Chinese Crackers blog [now closed] has done an excellent demolition job on the ‘evidence’ used for this claim, concluding:

To sum up – these figures are meaningless. They don’t measure foreign nationals or immigrants at all. They don’t tell us the number of crimes the people measured are responsible for – only the rate they are accused of crimes compared to the number of crimes people who describe themselves as British are accused of. As I’ve said before, there were 447,628 crimes reported in London in the first half of 2007. People describing themselves as non-British were accused of 22,973 of those – or 1 in 20 – and actually charged with 9,878 of them – or about 1 in 45. Saying ‘Foreigners are accused of a twentieth of crime in London’ or ‘Foreigners are responsible for one in forty crimes in London’ would be closer to the truth.

But if you can’t even be sure if they’re actually foreign or not, what’s the point?