A royal wedding is indeed the grandest, especially on how it is called "royal," there is no room for mistakes and only the strictest details to follow. It has been a common knowledge that there are protocols in royalty and within the royal family that is quite a lot and overwhelming for an ordinary citizen. But royals do have feelings, and they are not immune to being tired, lonely and sentimental, especially if they were exposed to common people and have already seen some extraordinary, like a disco ball.
Since every girl's dream was to marry a prince, Kate Middleton has waited so long and has been through an on and off relationship with Prince William. But it was her fate to become his bride and future Duchess of Cambridge, when Prince William finally proposed to her with Princess Diana's ring, on a trip to Kenya. Because of this outstanding patience exhibited by Kate Middleton, she and Prince William was an epitome of a traditional royal couple equipped with all the conservative royal rules from barely holding hands, to wearing stockings and the royal garb. Seemingly, all of these have prepared them for a bigger role that awaits them as Prince William becomes second in line to become the King of England.
However huge the role of Prince William will be in the future, Queen Elizabeth has always been fond of her grandsons, and the softest part of her heart would always be for Prince William and Prince Harry. Therefore, when Prince William would finally get to marry Kate Middleton, the wedding was expected to have the highest level of royalty in terms of its preparation and the guest lists. A special book entitled Kate: A Biography by Marcia Moody tells how The Queen intercepted the wedding in the way of breaking royal protocols. It was at that time when Prince William approached "Granny" about the occasion, and her answer was to simply "tear up the list and invite his friends," and from there they can start the wedding preparation.
In connection to Queen Elizabeth's advice, Prince Harry, who served as William's best man, and Pippa Middleton, sister of the bride, decorated the Buckingham Palace Throne Room with disco balls, bowls of the newlyweds' favorite candy and cocktails for a pre-reception party. Remembering Prince William and Kate Middleton's beaming smile on their wedding day can be well explained by the disco balls awaiting them, perhaps. But still, the exact permission to break royal wedding protocols was such a sweet gesture from Queen Elizabeth that the Duke and Duchess of Cambridge would forever cherish on their memories for a lifetime.