He collaborated with Eugenie's stylist Sarah Price to create the daring appearance, saying: "Much like Eugenie, the look is totally unique, and full of fun".
Tamara Beckwith, a friend of Eugenie's mother Sarah Ferguson, posted a sweet photo of her son enjoying a cupcake in a tent filled with lights, greenery and delicious snacks for attendees.
Dougal told the magazine that while normally royal wedding attire sticks with the convention of a long formal gown, the princess' third look reflected the "fun and informality" of the reception's festival theme.
A series of receptions took place in the Waterloo Chamber, the Grand Reception Room and St. George's Hall in Windsor Castle, with finger foods - including Yorkshire pudding bites and miniature Scotch eggs - and Pol Roger champagne on offer, People magazine reports.
The maid of honour is usually the one fixing the bride's dress but that job was left to Princess Eugenie's father, Prince Andrew, and Jack Brooksbank's best man. She was caught getting her toes sucked by her financial adviser and was also outed for accepting money to provide access to her former husband.
The Queen's husband is thought to have a frosty relationship with "Fergie", who divorced Andrew in 1996.
Royal Wedding: Princess Eugenie marries Jack Brooksbank in star-studded ceremony at Windsor
The newly married couple released four official portraits on Saturday, taken by photographer Alex Bramall at Windsor Castle, after their wedding ceremony on Friday.
Surrounded by their adorable bridal party at Windsor Castle, the happy couple were also joined by their parents, siblings and of course, Her Majesty the Queen and Prince Philip.
More than 800 guests attended the wedding, including pop star Robbie Williams and his wife, actress and TV presenter Ayda Field. This gave fans the first glimpse of the bride in her custom Zac Posen gown, which was inspired by the Windsor countryside.
In the fourth photograph, the newlyweds are pictured at the York family home, Royal Lodge in Windsor Great Park, ahead of the private evening dinner.
The colour reflects the blush of an English rose and Mr Posen is said to have taken his inspiration from the White Rose of York.
Eugenie was also wearing the Greville Emerald Kokoshnik Tiara loaned to her by the Queen.More news: Murdoch wants to replace Musk as chairman of Tesla
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