This document summarizes a study that used social network analysis to analyze the network of companies and individuals in London's advertising industry. The study found the industry to be relatively well-connected, with some individuals identified as key connectors between clusters who help spread knowledge. It also found that company size did not necessarily determine how central and important a company was to the network. Geographic proximity seemed to have more influence on network centrality than company size. The study demonstrated social network analysis can be a useful tool for economic geographers to examine industry networks.