Prince Philip missed the official birthday celebrations of his wife Queen Elizabeth II on Saturday. The 99-year-old's reason for being absent from the military parade hosted in honour of the queen at Windsor Castle was because of the fact that he has retired from public life in 2017. The prince who celebrated his milestone birthday on Wednesday has been isolating with his wife at the castle since March, when the UK imposed restrictions after the outbreak of coronavirus.

Queen Elizabeth II celebrated her official birthday with a scaled back Trooping the Colour parade at the castle. However, her husband Prince Philip was missing on the occasion as he retired in 2017.

"His Royal Highness The Duke of Edinburgh has decided that he will no longer carry out public engagements from the autumn of this year. In taking this decision, The Duke has the full support of the Queen... The Duke of Edinburgh is Patron, President or a member of over 780 organisations, with which he will continue to be associated, although he will no longer play an active role by attending engagements," Buckingham Palace told in a statement at that time.

However, this is not the first time the duke has missed the British monarch's official birthday celebration. The final Trooping the Colour that he attended was in the year of his retirement in 2017.

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💂🥁 Did you watch Her Majesty’s Official Birthday ceremony at Windsor Castle this morning? Typically, the Sovereign’s Official Birthday is marked with a Parade called Trooping of the Colour. This year, for the first time since 1955, Trooping of the Colour didn’t take place in its traditional form. Instead, the @welshguards performed a pared back ceremony for The Queen, with music from the Band of the @householddivision. Her Majesty, the Battalion’s Colonel-in-Chief, took the Royal Salute at the ceremony and watched a series of military drills - swipe to see a timelapse of this morning’s impressive display. Copyright: Press Association / @ministryofdefence

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Due to the coronavirus pandemic, the annual celebrations were cancelled. The members of the British royal family were unable to attend, but they got the opportunity to watch the celebration on TV alongside the rest of the nation.

The mini version of Trooping the Colour took place in a different format. The queen viewed the military ceremony in the Quadrangle of Windsor Castle. She added some cheer to the occasion by dressing up in a muted jade outfit by Stewart Parvin. She opted for a floral silk dress with pleated hem in jade grey and dusty pink, underneath a matching coat. She accessorised with a Rachel Trevor-Morgan hat and a brooch of the Welsh Guards – a diamond leek.

Queen Elizabeth II and Prince Philip
Britain's Queen Elizabeth II and Prince Philip, who is undergoing hospital treatment for what Buckingham Palace described as a "pre-existing condition" Photo: AFP / Fiona HANSON

The queen watched soldiers from the 1st Battalion Welsh Guards, who are currently on guard at Windsor Castle, and a music performance by a Band of the Household Division. She was given a royal salute. The event concluded with a second salute before she departed.