By DAILY MAIL REPORTER
All the Queen's horses: Soldiers of the Household Cavalry cross Horse Guards Parade in London as they take part in the Royal Wedding dress rehearsal
Hundreds of soldiers, sailors and airmen today had their last chance to practise for Friday's Royal Wedding in a dress rehearsal that started before dawn and continued into daybreak.
The full-scale walk-through was timed down to the last second - with military leaders well aware that the world will be expecting them to make sure everything goes smoothly on the big day.
So nothing was left to chance with the dry run which began at around 4.50am - after soldiers had gathered as early as 2am - and continued for hours.
Here comes the bride? A carriage is escorted across Horse Guards Parade in a cloud of dust, accompanied by soldiers and mounted police
Meanwhile: Dressed in a demure cream suit, Kate drives from her family home in Bucklebury, West Berkshire, with a protection officer beside her
All the participants wore uniform - but the cavalry were in olive green jackets instead of the red and silver they will wear on the big day - and the Rolls-Royce that will carry Kate and her father to Westminster Abbey was 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 of Rolls-Royces which pulled up at about 4.50am.
Here comes the bride: The Royal Rolls-Royce that will carry Kate Middleton and her father is seen with police escort as it arrives at Westminster Abbey
Practise hard, marry easy; A carriage followed by a cavalry soldier leaves Westminster Abbey
Farewell: It is likely Kate Middleton will not return to her family home until she is a married woman
Shortly after 5am the action began.
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 end 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.
Dawn patrol: Two mounted officers ride past sailors lining the route to Parliament Square
Members of the British Royal Navy march towards Westminster Abbey (left), while a mounted officer waits outside Westminster Abbey
'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 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.
Dedicated followers: Royal fans who are already camping out ahead of the wedding awoke to the spectacle
All present and correct: Sailors stand to attention as a mounted officer passes
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.
Organisers said the dry-run went without a hitch and forces personnel were slightly ahead of time.
The walk-through came after Westminster Abbey closed its doors to the public yesterday to prepare in earnest for the wedding.
The first of the floral decorations that will adorn the abbey began arriving last night including a 20ft-high English field maple.
The tree, which weighs more than half a ton and is 18 years old, will be part of an "avenue of trees" which will line the aisle leading to the altar.
A music rehearsal is scheduled to be held today with clergy and broadcasters due to take part in a full dress rehearsal tomorrow at the abbey.
At some stage, the prince and his fiancee will hold their own preparations with senior clergy at the abbey.
Meanwhile, detectives leading the security operation for the royal wedding have appealed for the public to be the 'eyes and ears' of the 5,000 officers tasked with maintaining law and order on the big day.
Scotland Yard's appeal to the hundreds of thousands of people expected in central London to celebrate came as officers revealed another protest group with Middle Eastern links has warned it plans disruptions at the royal wedding.
The Metropolitan Police is already negotiating with extremist campaign groups Muslims Against Crusades (MAC) and the English Defence League over proposed protests.
To the Palace: A sergeant major looks on as three mounted officers make their way towards Buckingham Palace
Eyes front: A soldier is instructed by a sergeant major outside Horse Guards
All their finery: On Friday the cavalry will don their ceremonial red jackets
Royal wedding rehearsal
Gráinne Seoige - The Royal Wedding Route - Daybreak 27/4/2011
Raw Video: Military Rehearses for Royal Wedding