Crowds are gathering today in central London for the wedding of Prince William and Kate Middleton at Westminster Abbey.Reports say thousands of people have camped out overnight on the procession route the couple will take to Buckingham Palace.
The couple is to brave the risk of showers and use an open-topped 1902 State Landau carriage for the procession after the service.
It is the carriage in most general use at Buckingham Palace and is often used by the Queen to meet visiting foreign heads of states.
The Met Office says the day will start off dry but cloudy in London and there is a risk of heavy showers developing later on.
The prince will wear the red tunic of an Irish Guards colonel – his most senior honorary appointment – but the bride’s dress design is being kept secret.
On Thursday night, Prince William went on an impromptu walkabout to meet royal watchers who had thronged to The Mall, near the palace.
He spent several minutes shaking hands, chatting and posing for pictures telling well-wishers: “All I’ve got to do is get the lines right.”
The prince spent Thursday evening with the Prince of Wales, Duchess of Cornwall and Prince Harry, while Miss Middleton and her family gathered at the Goring Hotel, in Belgravia, a short distance from Westminster Abbey.
Scotland Yard says 5,000 officers will be on duty, with more than 900 along the wedding route. Most will be in uniform, but some will be in plain clothes, mixing with the crowd.
Elsewhere in the UK more than 5,500 street parties are taking place – including one hosted by Prime Minister David Cameron at Downing Street and another by the anti-monarchy campaign group Republic.
After the service, five carriages drawn by mounted troops of the Household Cavalry will carry the newlyweds, the Royal Family and the Middleton family on the 15-minute journey from Westminster Abbey to Buckingham Palace.
The route will take them past the Houses of Parliament and Downing Street and, under rows of Union Jacks, along The Mall, to Buckingham Palace, where the couple will appear on the balcony at about 1325 BST.
Royal officials said William and Kate have been involved in planning their wedding day, from the music at the ceremony to the flowers and the cake.
Inside Westminster Abbey itself, six field maples and two hornbeams will line the aisle leading up to the altar.
Some 650 guests have been invited to the palace for a buffet lunch and about 300 close friends and relatives will stay on for formal black tie dinner and disco in the evening.
But the Queen and the Duke of Edinburgh will leave for a weekend away after hosting the lunchtime reception and will miss Prince Harry’s best man speech and Michael Middleton’s father of the bride address.
The Archbishop of Canterbury will conduct the wedding ceremony, which will see Miss Middleton vow to “love, comfort, honour and keep” Prince William but not to obey him.
In their official wedding programme released on Thursday, the royal couple said: “We are both so delighted that you are able to join us in celebrating what we hope will be one of the happiest days of our lives.
“The affection shown to us by so many people during our engagement has been incredibly moving, and has touched us both deeply.”
Prince William’s choice of a military uniform for his wedding is something of a surprise, royal watchers say. As a search and rescue helicopter pilot in the Royal Air Force, many had predicted he would wear his blue flight lieutenant’s uniform.
Prince Harry is a captain in the Household Cavalry’s Blues and Royals regiment and will wear his uniform, while Prince Charles will be in his Royal Navy admiral’s outfit.
The bride will walk up the aisle to coronation anthem I Was Glad, by Sir Charles Hubert Hastings Parry, from Psalm 122.