The 92-year-old monarch's health concerns are not believed to be major, with a spokesperson telling Telegraph UK that no doctor or hospital was involved.
Her Majesty still plans to travel to Windsor in the afternoon, where she'll spend the weekend before heading to Scotland as planned early next week, for a number of engagements there.
Her Royal Highness underwent surgery last month to remove a cataract from her eye, Buckingham Palace announced earlier.
Her Majesty 'successfully underwent a short planned procedure', a spokesman from the palace said.