The agents of the Ministry of Extraordinary Threats are not stupid people- just very, very determined. They're also prone to doing their research, particularly when they've got to operate outside their own borders. While they've got a measure of power and something like a limited form of diplomatic immunity in a lot of the Commonwealth countries, the United States is chancy ground at best- for now, anyway.

There's a fire escape overhead on the wall of the building opposite the store Tyler's headed towards. It's a great place to stash tiny cameras, or very patient people in unspectacular-looking clothing who carry dart guns, or both.