The vital work of the security services to protect against terrorism should not be overlooked, a former MI6 chief has said, as the world marks the 20th anniversary of the 9/11 terror attacks on the U.S. Sir Richard Dearlove, who headed the secret intelligence service between 1999 and 2004, told a memorial event in London that “we owe a debt to the diligence and skill of the women and men of our intelligence and security community”. He was speaking in front of a four-tonne twisted piece of steel from the ruins of New York’s Twin Towers which has been forged into a memorial artwork at London’s Olympic Park. Sir Richard told those gathered at the memorial: “On the 20th anniversary of 9/11 I ask you to also remember the work of my former colleagues in helping to keep us safe in this day and in this world. “Events in Afghanistan …