Australian and New Zealand forces who paid the ultimate sacrifice have been remembered at a moving dawn service.
Anzac Day was marked with the religious gathering at London's Hyde Park Corner where Antipodeans honoured their First World War dead and those who have served in subsequent conflicts.
The Duke of York - who served in the Falklands War - laid a wreath in remembrance of those who died.
The High Commissioner of New Zealand Sir Jerry Mateparae, his Australian counterpart Alexander Downer and the chief of the defence staff, Air Chief Marshall Sir Stuart Peach, also laid wreaths.
Professor Tom Frame, former bishop to the Australian Defence Force, delivered the prayer of remembrance for those gathered at the Australian War Memorial at Hyde Park Corner.
He said: "Lord God, as the sun rises this new day, as it rose on the first Anzac Day, we remember the sacrifice of those who served, suffered and died in Turkey, and those who have given of themselves to advance the cause of liberty and peace."
He went on to say: "While we remember the mateship, agony, courage and compassion of war service, save us from the pride and the hubris that might ever lead us to think war is anything other than a human tragedy."
Anzac Day - April 25 - marks the anniversary of the start of the First World War Gallipoli landings, and is a national day of remembrance for Australia and New Zealand.
Thousands of Anzac troops - Australian and New Zealand Army Corps - died in the ill-fated 1915 campaign.
Waves of Allied forces launched an amphibious attack on the strategically important Turkish peninsula, which was key to controlling the Dardanelles straits, the crucial route to the Black Sea and Russia.
But the plan backed by Winston Churchill, then first lord of the admiralty, was flawed and the campaign, which faced a heroic defence by the Turks, led to stalemate and withdrawal eight months later.
Its legacy is the celebration of the "Anzac spirit" - courage, endurance, initiative, discipline, and mateship - shown by the Antipodean troops and today the Anzac Day service in London has become an important moment for thousands of New Zealanders and Australians.
During the service hymns were sung and the Last Post was sounded by a bugler and a minute's silence was observed by all as the sky lightened before the dawn.
Anzac Day will also be marked by a wreath laying ceremony and parade at the Cenotaph later, due to be attended by the Defence Secretary Sir Michael Fallon and other dignitaries.
Later the Duke will join the congregation at Westminster Abbey for a Service of Commemoration and Thanksgiving.
The Defence Secretary said: "On Anzac Day we remember the sacrifice and courage of troops from Australia and New Zealand. Britain is proud to have served alongside our Anzac allies in conflicts from the fields of Flanders to our modern day battle against Daesh.
"Our alliance is one of the most consistent and enduring military partnerships in history, one which will continue to protect our common interests and help make the world a safer, more secure place."