The Bali bombings left an "indelible mark" on Britain's national memory, Foreign Office minister Hugo Swire has said.
Mr Swire joined relatives and friends of the 28 Britons who lost their lives on October 12 2002 to mark the 10th anniversary of the terror attacks.
A total of 202 people, including 28 Britons, were killed on October 12 2002 and more than 204 injured when the al Qaida-linked Jemaah Islamiyah group detonated bombs at two packed Bali nightspots.
Hundreds of people, including Australian Prime Minister Julia Gillard, as well as Britain's ambassador to Indonesia, gathered on Friday for a ceremony on the island, where more than 2,000 police and military, including snipers, guarded the service amid security concerns.
And in London, families and friends of the British victims attended a closed ceremony at the memorial to the victims of the bombings, at St James's Park. They were joined by Foreign Office minister Hugo Swire, who made a brief speech before laying a wreath.
He told the gathering: "I am reminded of it as I pass this memorial each morning on my way into the office. The 202 names inscribed here include also the Indonesian bystanders - those who were not targeted, but killed nevertheless. The names include people of 23 different nationalities and from all six continents.
"They do not include the names of those who remained unidentified. But our thoughts go out to those from whom they were so suddenly taken.
"The bombers hoped to spread terror - and indeed they did. But the legacy of those crimes is not terror. The legacy is the stories of bravery about those who compromised their own safety to help rescue the injured.
"It is the solidarity of people and governments all around the world - of different races, religions and political beliefs - who deplored the attacks and all they stood for, and who mark this sombre anniversary today."
Diplomats from other nations that lost people, as well as relatives, also laid wreaths, before attending a brief reception at the Foreign Office.