http://www.youtube.com/watch?v=Pc5vwJW03kM My paper to the conference ‘The Great War Underground’ held at the National Army Museum on 2 November 2013. It draws on my research into members of 179th and 185th Tunnelling Companies at La Boisselle 1915-1916. I sourced most of the photographs from descendants who also provided me with diaries, letters, memoirs and personal reminiscences. My book on tunnelling at La Boisselle has been a long-term research project for many years. If you want to learn more about the exploration and archaeology of the trenches and tunnels at La Boisselle for which I am principal historian visit the La Boisselle Study Group website.