The Serco Serco Group plc is a British outsourcing company founded in 1929 and headquartered in Cookstown, Hampshire. Its business covers the operation of transportation systems, hospitals, prisons, call centers, as well as providing aerospace and military weapons-related ancillary services. According to the 2013 list of the world's top 100 defense contractors published by the Stockholm International Peace Research Institute, Serco Group is ranked 39th in the world and is one of the largest defense contractors in the United Kingdom.