Historian specializing in the classical and medieval world. He is the author of the DK Companion Guide to World History (2010), The Empire Stops Here: A Journey Around the Frontiers of the Roman Empire (Jonathan Cape 2009), The Northmen's Fury: A History of the Viking World (Jonathan Cape 2014), Revolution (Andre Deutsch, 2017). He was co-author of The Times History of the World in Maps (2014) and General Editor of The Great Trade Routes: A History of Cargoes and Commerce Over Land and Sea (Anova 2012). He was a contributor to DK History Year by Year (2011) and DK History of the World in 1000 Objects (2014). He previously worked as a diplomat and a publisher of historical atlases.