Members of the royal family got up close and personal with some of the guests as they cheerfully posed for photos with the crowds. Prince Harry was spotted happily stopping to pose for a selfie with a group of revellers, while Princess Eugenie and Princess Beatrice smiled as one fan took a photo with them. Beatrice was even spotted helping one attendee get the perfect picture when she held the phone herself to ensure they were both in the snap.
Meanwhile, Prince William caught out one fan who was so determined to get a selfie with the father-of-two that she spoke to him twice, by running down The Mall to see him again. However, the Prince wasn't fooled and recognised her, reportedly telling her: "I always know a face".
Prince Philip and the Duchess of Cambridge share a private joke
Spirits were high as the parade kicked off and the sun finally came out, and the royal family couldn't hide their excitement, laughing and talking as they enjoyed the striking performances put on by the Patrons.
Clearly enjoying the day's festivities, Kate was spotted chatting with Prince Philip, with the Duke of Edinburgh causing her to burst into a fit of giggles as the pair shared a joke.
Lady Louise Windsor's first royal walkabout
Prince Edward and the Countess of Wessex's daughter Louise charmed the crowds as she embarked on her first ever royal walkabout. The 12-year-old took time to speak to those who had braved the weather for the celebrations, even admitting to one fan that she found it "a bit daunting."
Lady Louise wasn’t joined by her brother James, Viscount Severn, as he was attending a friend's birthday party.
"I thanked her for coming especially in the rain and she told me it was her first walkabout," said Eve Pollecoff, 86, who had the chat with the young royal. "I asked her if it was difficult talking to strange people. She said it was a bit daunting but she had a great example in her father."
The public braving the British weather
The celebrations may have been hit by heavy rain, but revellers at the Patron's Lunch didn't let the downpours dampen their spirits.
Many pulled out all the stops for the occasion with Union Jack-themed outfit or even fancy dress, covering with plastic ponchos and umbrellas to face the wet weather for the festivities on the Mall.
Prince Charles and Camilla go solo at local street party
Prince Charles and the Duchess of Cornwall joined in the fun at a street party in Gloucestershire, where they met with royal wellwishers who had pulled out all the stops for a royal-themed fancy dress competition, with some children dressing up as everything from guards to princesses.
The couple then joined local residents for The Big Lunch where they ate egg sandwiches and cakes.
Princess Michael of Kent commemorating the moment
Despite the gloomy weather, the atmosphere on Sunday was electric as crowds gathered for the celebrations, cheering as the royal family made their way down The Mall.
Therefore, it comes as no surprise that Princess Michael of Kent was spotted immortalising the moment as she took photos of the event on her phone.
The Queen and Prince Philip making their way down The Mall
The Queen was as elegant as ever in a chic pink ensemble as she arrived for her birthday celebrations, joined by Prince Philip as she waved to the cheering crowds.
As the couple were driven to the Admiralty Arch Stage - where the Queen would later give a speech - the Duke of Edinburgh caused a giggle amidst fans when he was spotted asking their driver to slightly speed up so that the pair wouldn't be late.
The Duke and Duchess of Cambridge share an affectionate moment
Prince William and Kate shared a sweet moment when leaving the Patron's Lunch following the lively parade.
The prince put his hand on the Duchess of Cambridge's back as they made their way out of the box, while Zara Tindall was caught smiling at the content couple in the background.
The unrivalled atmosphere
With ten thousand revellers heading to The Mall to celebrate the Queen's 90th birthday, it comes as no surprise that there was a fantastic atmosphere. Despite the rain, crowds gathered to wish the Queen a happy birthday, packing picnics and singing songs.
They continued to cheer as the royals arrived, and sung along to the music that played throughout the parade, before joining forces for a memorable rendition of Happy Birthday to the Queen for the parade's impressive finale.
The British royal family gather for group photo
After the celebrations had finished and revellers began heading home, the British royals took a moment to gather and pose for a striking family photo, to commemorate the exciting day. The Duke of York took on the responsibility of photographer as he quickly took the snap, while the Queen observed the proceedings from her car.