Britain and America will "never to give in to those who mean us harm", Boris Johnson insisted in a tribute to those killed in the September 11 attacks. London's mayor was given a tour of the memorial created to mark the 2001 tragedy by co-founder of the Tribute Centre Lee Ielpi, whose firefighter son Jonathan died trying to save others.
Johnson left flowers with a message that read: "The people of London will never forget the thousands who lost their lives on 9/11 2001. We honour the memory. We remember the sufferings of their families and all the bereaved. Our two cities embody the highest values of our civilisation: freedom, democracy, pluralism and tolerance. We are jointly resolved never to compromise those values and never to give in to those who mean us harm."