By Andy Milne
Tense moment: Prince William puts the ring on Kate, Duchess of Cambridge's finger during their wedding ceremony at Westminster Abbey
It was the moment two billion people held their breath.
As William put the ring on his bride's finger in Westminster Abbey, for just a second, it looked like it wouldn't fit.
But the prince managed to stay cool in a tight spot, no doubt helped by his time at Sandhurst, and struggled the simple gold band into place.
It was the only tense moment of a spectacular fairytale ceremony inside Westminster Abbey.
Struggle: William had to apply a considerable amount of pressure to get the ring into place. But he stayed cool and eventually got the simple band into place
The future king and his bride, who will now one day be queen, pledged their love for one another in the ancient surroundings, watched by two billion across the globe.
The Rolls-Royce carrying the bride arrived Westminster Abbey at 11am as the church bells rang out.
When her father took her left hand they began their procession along the red carpet that started outside the ancient building and led inside, with her sister Pippa carrying her train.
The Dean of Westminster greeted the bride and her father and the pair paused as final adjustments were made to the dress before the procession began.
As her young bridesmaids and pageboys assembled behind her in the nave, beneath the impressive 18th-century stained glass West Window, Miss Middleton was able to take in the abbey's shimmering Waterford crystal chandeliers and vast gothic arches above her.
Arrival: Prince William and his best man Britain's Prince Harry arrive at Westminster Abbey
Here come the relatives: Princess Beatrice and Princess Eugenie, left arrived after Carole Middleton, right, who chose a sky blue outfit
More royalty: Zara Philips chose a grey outfit with a striking slanted hat, while Prince Edward arrived in military uniform
Proud moment: The Prince of Wales and the Duchess of Cornwall wave as their car makes its way to the Abbey
Here to see her son: The Queen greets The Right Reverend Dr John Hall, Dean of Westminster at the Abbey
Royal arrival: Prince Charles and Camilla arrive at Westminster Abbey followed by Queen Elizabeth II and Prince Philip. Senior politicians are sitting in the stalls behind the choir
Her big moment: Kate Middleton arrives with her father Michael Middleton and her sister Philippa Middleton at the West Door of Westminster Abbey
Soaking it all up: Philippa Middleton looks after the junior bridesmaids as Kate waves to the crowds outside the Abbey
Time to go inside: Philippa Middleton gathers the bridesmaids and page boys and takes them into the church
Here we go: Kate Middleton heads inside with her father Michael as her sister Pippa holds her dress
A fairytale begins: The Dean of Westminster greats the bride, left, and she walks through the avenue of trees with her father Michael
Nerves jangling: The bride walks through the avenue of trees as she enters the Abbey
Here comes the bride: Kate Middleton is led by her father along the aisle at Westminster Abbey as senior politicians including Ed Miliband, the Prime Minister and William Hague look on
Cavernous ceilings: Kate walked up the aisle to the sound of coronation anthem Parry's I Was Glad
Ceremony begins: The first hymn sung was Guide Me O Thou Great Redeemer, which was the last sung at Princess Diana's funeral
On her father's arm, Kate walked up the aisle as a commoner to the sounds of the coronation anthem, Parry's 'I Was Glad'.
When they arrived at the altar Prince William apparently cracked a joke to his father-in-law, according to a lip-reader, saying: 'We're supposed to have just a small family affair.'
Moments earlier, William's best man Prince Harry apparently told his brother: 'Right she is here now.'
As her groom waited, Kate moved along the red carpet, around the south side of the poppy-lined Grave of the Unknown Warrior - the only gravestone in the abbey over which it is not permitted to walk.
Behind her was her maid of honour and sister charmingly holding hands with the youngest of the bridesmaids Eliza Lopes and Grace van Cutsem - both just three-years-old.
Knelt in prayer: The bride and groom were married by the Archbishop of Canterbury
Brothers and sisters: Best man Prince Harry and chief bridesmaid Phillipa Middelton follow the husband and wife out the Abbey to a crowd of adoring royal fans
They were followed by Lady Louise Windsor and the Hon Margarita Armstrong-Jones, and then the page boys Tom Pettifer and Billy Lowther-Pinkerton.
Walking through the 'avenue of trees', Kate processed past delighted guests seated facing inwards in the nave before moving through the intricate golden quire screen, on top of which sit the orchestra, and into the quire.
In the Victorian gothic wooden stalls lined with red lamps, sat Prime Minister David Cameron and other senior politicians and high commissioners, as well as the two choirs and their schoolboy choristers.
Here, Miss Middleton made her way to the Lantern, where she finally met William, resplendent in his dashing red Irish Guards uniform, at the Sacrarium steps.
In the south transept stood William's grandparents the Queen and the Duke of Edinburgh, his father the Prince of Wales and stepmother the Duchess of Cornwall, and other members of the Royal Family.
In the north transept were the Middletons and many of William and Kate's close friends.
Husband and wife: The royal couple leave the Abbey after the ceremony. Kate's dress was designed by Sarah Burton. William wears his ceremonial Iriah Guards uniform
You look beautiful: Kate Middleton and Prince William hold hands as the Archbishop of Canterbury Dr Rowan Williams conducts the service
The first hymn, Guide Me, O Thou Great Redeemer, rose high into the nave as the choirs of the abbey and Her Majesty's Chapel Royal, St James's, led the congregation in singing.
Dean of Westminster Dr John Hall began the service with the famous words: 'Dearly beloved, we are gathered here in the sight of God and in the face of this congregation, to join together this man and this woman in holy matrimony...'
The cleric went on to utter the immortal lines: '...if any man can shew any just cause why they may not lawfully be joined together, let him now speak, or else hereafter forever hold his peace.'
Before beginning the marriage ceremony, the Archbishop asked the couple if there was any reason why they could not wed.
He said to the bride and groom: '...if either of you know any impediment, why ye may not be lawfully joined together in matrimony, ye do now confess it.'
The only two acceptable reasons would be if couple were too closely related or if either were already married.
William spoke in public for the first time today when he replied 'I will' in a clear and strong voice to the Archbishop of Canterbury's question about whether he would 'love, comfort, honour and keep' Kate.
His bride spoke more softly when she said 'I will' in response to the same question.
Kate looked nervous and at several points appeared slightly choked with emotion as she repeated her vows in front of the large congregation.
In his address, the Bishop of London, the Rt Rev Richard Chartres, read a prayer penned by William and Kate.
Fairytale ceremony: Prince William and the new Duchess of Cambridge leave the Abbey
Honour guard: Soldiers, sailor and airmen follow the royal couple away from the Abbey
The fairytale continues: Guests awaiting the arrival of the bride at the beginning of the ceremony
The newlyweds asked for spiritual help to maintain focus on the things that mattered, and to be "generous" with their "time and love and energy".
They also called on God to help them 'serve and comfort those who suffer' - a declaration of intent for their new life together.
The bishop, who has close links to the groom and his family, told the congregation: "I pray that everyone present and the many millions watching this ceremony and sharing in your joy today will do everything in their power to support and uphold you in your new life.
'I pray that God will bless you in the way of life you have chosen, a way which is expressed in the prayer that you have written together in preparation for this day.
'God our Father, we thank you for our families; for the love that we share and for the joy of our marriage.
'In the busyness of each day keep our eyes fixed on what is real and important in life and help us to be generous with our time and love and energy.
'Strengthened by our union, help us to serve and comfort those who suffer. We ask this in the Spirit of Jesus Christ. Amen'."
The couple and their immediate family enjoyed their only private moment of the service when they retired to the abbey's holiest area to sign the registers.
The bride and groom were joined by Charles and Camilla, Michael and Carole Middleton, best man Harry and Kate's brother James and sister Pippa in the tiny enclosed Chapel of St Edward the Confessor behind the altar.
After a few minutes the newlyweds were left on their own for a period with just Harry and Pippa.
When they emerged, the couple approached the Queen and paused to pay their respects to the monarch.
Kate gave a low curtsy - the first time she has formally acknowledged the sovereign in public - while William nodded to his grandmother.
A special fanfare entitled Valiant And Brave - after the motto of the Prince's RAF Search and Rescue No 22 Squadron - was played.
The 30-second newly commissioned celebration was sounded by seven trumpeters and one drummer from the Central Band of the RAF.
The bride and groom then processed down the nave with Harry and Pippa behind them arm in arm, moving on to the adoring crowds outside.