The British Ministry of Defence said a Royal Marine has been shot dead in southern Afghanistan, the fourth from 40 Commando to die in as many days. <br/><br/>The marine was conducting a security patrol to reassure locals in the Sangin district of Helmand province when he was shot by insurgents today. A total of 304 UK service personnel have now been killed in Afghanistan since the conflict began in 2001.<br/><br/>