The Duke and Duchess of Sussex shared a carriage with the Duchess of Cambridge and Duchess of Cornwall as they made their way from Buckingham Palace down The Mall to Horse Guards Parade.
The annual parade marks the Queen’s official birthday. Her Majesty actually turned 93 on April 21.
But why didn’t Harry, 34, join his father Prince Charles and brother William on horseback during the procession?
The duke does not ride on horseback during the parade because he does not hold the position of a royal colonel.
Prince Charles (Welsh Guards), Princess Anne (Blues and Royals), Prince Andrew (The Grenadier Guards) and Prince William (Irish Guards) ride on horseback for Trooping the Colour because they are colonels of the Household Division.
The Queen used to attend on horseback herself, but in recent years has travelled by carriage. She last rode on horseback in 1986.
Harry sported his Blues and Royals uniform with aiguilettes (gold grading on the shoulders). He served with the British Armed Forces for ten years, leaving his post in June 2015.
He and wife Meghan welcomed their first child on May 6. Archie Harrison Mountbatten-Windsor was born at 05:26 at The Portland Hospital.
The seventh in line to the throne made his debut to the world two days afterwards when Harry and Meghan held a brief photocall at Windsor Castle.
The duchess is expected to remain on maternity leave from royal duties until autumn, but may make appearances at formal events inbetween.