Only one main interface to the Internet???

Very interesting article about a potential plot to disrupt Britain's Internet access...One item that jumps out at me:

Raids by Metropolitan Police detectives found computer files indicating that terrorist suspects had targeted a high-security Internet "hub" in London that handles most of the Internet information that passes in and out of Britain, including London's businesses and stock exchange, the Sunday Times said.

The first question that comes to mind...is "Why does Britain have only one main hub to handle the majority of their Internet traffic?

This flies against the security principle of redundant systems.

Chalmer