That's interesting, but it doesn't address to what extent someone in the City of London could skirt British laws or taxes as the article implies. In 1771, the aldermen of the City of London were able to bar Parliament from entering the City of London to arrest a newspaper publisher who had broken the law by publishing transcripts of Parliamentary debates. Does the City of London still have that kind of autonomy?

No. It has a separate police force, but I don't think the boundaries are as strict as they are for, say, state boundaries in the US. Pretty sure a Met Police Car wouldn't stop a pursuit because it entered the city.

//edit//Although in Victorian times I believe it did inhibit attempts to capture Jack the Ripper.

Indeed, all Police Officers in the country have their powers throughout the whole country, regardless of which Force they belong to. There are courtesy’s that are usually observed when crossing into another force area in pursuit of a criminal, the control room of the other force is informed (and usually asked for help), and local officers will often take over or lead the pursuit if they are available, though this is more because they know the area better. Upon arrest, the criminal will usually be "booked in" at the local police station but then transported back to one of the original force's police stations for processing. Criminal law is the same across the country, so there is no sense of different jurisdictions. There are some more formalities going into Scotland, which has slightly different criminal laws, but nothing that stops a good chase! Theres no benefit to the criminal of "getting across" internal borders (akin to state lines in the US). Getting across a border externally means crossing the sea, and even then co-operation between European forces is getting better.

If they are non domiciled for tax is the normal way they do this.

I remember being utterly perplexed when I found out that there is a "Mayor of London" and a "Lord Mayor of London". :P