Up to a thousand members of the military carried out a pre-dawn royal wedding dress rehearsal today.
The full-scale walk through in preparation for Friday's big day involved the Army, Navy and RAF.
The eyes of the world will be on Prince William and Kate Middleton when they begin their journeys to and from Westminster Abbey.
And it falls in no small part to the military to ensure the couple's occasion has all the pomp and grandeur it deserves.
So nothing was left to chance with the dry run in which timings were tested to the second and all armed forces taking part got the chance to practise their role in full ceremonial dress and ensure nothing is left to chance.
The day began very early - about 2am for those involved.
Forces left Westminster's Wellington Barracks shortly before 5am to begin their way along the route.
Some of the soldiers, sailors and airmen practising their duties were Prince William's colleagues.
First to arrive at the abbey were two of the royal fleet cars - Rolls-Royces which arrived at about 4.50am.
Shortly after 5am the action began.
It was audible only at first as the sounds of orders being barked out emerged from the final stretch of the route running down from the Houses of Parliament to the abbey.
Several companies of the Royal Navy lined the conclusion of the route, preceded by the Army lining Parliament Street.
Soldiers lined the route up to the Cenotaph, outside the entrance to Downing Street.
From there the RAF lined the road up to Horse Guards Parade which the royal convoy will pass through on Friday.
An RAF officer walked the line.
"On the day you'll have your heels on the white line (of the road markings)," he told them, making sure they knew to take an extra step back closer to the crowds.
When the Ministry of Defence announced the Armed Forces' extensive ceremonial role, General Sir David Richards, head of the military, described it as a "huge honour" for those involved.
When the couple leave the abbey as man and wife, two groups of 12 military personnel will line their route as they make their way to their horse-drawn coach.The tribute is traditionally performed at many military weddings.
Dozens of soldiers on horseback from the Household Cavalry made their way to Westminster Abbey via a different route from the wedding cars this morning.
The cavalry, who led the cars and carriages back to Buckingham Palace through the arch of Horse Guards Parade and along the Mall, performed a loop, parading down Buckingham Palace Road and along Victoria Street to get them to the Abbey.
As the horses walked through the parade ground at Horse Guards, clouds of dust kicked up covering the Welsh Guards, who were lining that part of the procession.Reuse content