Final poppy planted for British WWI dead during moving ceremony in London

A teenage army cadet has planted the last of 888,246 ceramic poppies at the Tower of London, representing every British military fatality in World War I, as the country marked Armistice Day.

A century on from the start of the 1914-1918 Great War, people around Britain on Tuesday stood for the traditional two-minute silence remembering all those who have given their lives in conflict.

Cadet Harry Hayes, 13, was watched by a crowd of thousands at the Tower of London as he completed the installation Blood Swept Lands and Seas of Red.

The vast artwork, filling the moat surrounding the 11th-century fortress with a blood-red tide, has captured the public imagination and become the focal point for World War I centenary commemorations.

An estimated five million people have been to the castle to see the poppies - the symbol of remembrance - and in recent days, the floodlights have been kept on so people can visit through the night.

"We always hoped the installation would capture the public imagination yet we could not predict the level of support we have received," said former army chief General Richard Dannatt, now the Constable of the Tower of London.

The two-minute silence at 11am marked the end of World War I at the same time on November 11, 1918.

Prime Minister David Cameron paid his respects at the Cenotaph, while thousands more people massed in the nearby Trafalgar Square.

Outside St Paul's Cathedral, hundreds of city workers stood together in silence as the dean led a service of prayer from the steps. Traffic came to a standstill as the bells chimed 11.

The England football team, training at their St George's Park base in Burton, central England, were joined by members of the armed forces in marking the silence on the main pitch.