Prince Harry has laid a wreath at Wellington Arch to mark the start of Anzac Day commemorations in the UK.
Thousands of people attended the dawn service, which marked 100 years since the day was first marked in London.
Anzac Day (the Australian and New Zealand Army Corp) has been commemorated in London since the first anniversary of the Anzac landings at Gallipoli in 1916, when King George V attended a service at Westminster Abbey.
In a speech at the service, Alexander Downer, Australian high commissioner to the UK, said: "When we reflect on Anzac Day we imagine the Gallipoli landings, what it must have been like, at dawn on the water, in sight of that rugged shoreline - and a collectively held breath, a leaden silence about to be broken.
"We consider the enthusiasm, the courage, and the heroism of the Anzac troops - ordinary men fighting for God, King and empire, for their mates, for adventure, for a world without war."
Harry will later attend a parade at the Cenotaph, where he will lay a wreath on behalf of the Queen, and a service of commemoration and thanksgiving at Westminster Abbey.