The responses below are correct - the analysis in the article is about a smaller region of London, that essentially falls inside the large peak in the plot. I w

The responses below are correct - the analysis in the article is about a smaller region of London, that essentially falls inside the large peak in the plot. I wasn't deliberately avoiding this point, it's just that the article was getting long and I wasn't sure how much detail to keep in. I've made a correction to the post to alleviate this confusion. And thanks for pointing this out.