The Queen's Platinum Party at the Palace is expected to begin in the coming hours, but the Duke and Duchess of Sussex will not be present at the event.
More than 30 members of the Royal Family are expected to attend the Platinum Party at the Palace which is set to draw crowds of 22,000 people.
The Prince of Wales and the Duke of Cambridge will lead tributes to the Queen, marking her 70-year reign.
Her Majesty is expected to watch the star-studded event from the comfort of Windsor Palace, after she pulled out of yesterday's service at St Paul's and the Epsom Derby this afternoon.
The Duke and Duchess of Sussex will not be attending the concert
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The Duchess of Cornwall and Kate Middleton, Duchess of Cambridge will attend the concert, watching acts including Diana Ross and Alicia Keys.
A spokeswoman for the Duke and Duchess of Sussex told PA news agency the couple were spending the day privately.
Harry and Meghan will be celebrating their daughter Lilibet's first birthday today, with members of the Royal Family sending their well wishes via Twitter this morning.
On Friday, the Duke and Duchess of Sussex made their first public appearance alongside the Windsors at the Service of Thanksgiving, following their departure to the US in 2020.
Prince Charles and Prince William will lead tributes to the Queen, marking her Platinum Jubilee
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The Duke and Duchess of Sussex were absent from the Thanksgiving reception, held at the Guildhall following the service.
Harry and Meghan were spotted holding hands and smiling broadly as they walked up the steps of the cathedral.
The Duke and Duchess of Sussex were seated in the second row of the congregation for the Service of Thanksgiving, alongside Princesses Beatrice and Eugenie and their husbands, and Lady Sarah Chatto, the daughter of Princess Margaret, and her family.
The couple and their two children, Archie and Lilibet, flew via private jet to the UK from their California home, and transported from Farnborough airport to their Windsor home, Frogmore Cottage, by bullet-proof cars sent by the Queen.
Other royals are anticipated to be out in force to watch acts including Queen and singer Adam Lambert and Craig David include the Earl and Countess of Wessex and their children Lady Louise Windsor and Viscount Severn, the Princess Royal and Vice Admiral Sir Tim Laurence, Princess Beatrice and her husband Edoardo Mapelli Mozzi, and Princess Eugenie and her husband Jack Brooksbank.
Princess Anne’s son Peter Phillips is expected to be joined by his children Savannah and Isla, while Zara and Mike Tindall, who spent the day at the Epsom Derby with Anne and Sir Tim, will also present.
The Queen’s cousins – the Duke of Gloucester, the Duke of Kent and Prince Michael of Kent – with the Duchess of Gloucester and Princess Michael of Kent – and Princess Margaret’s daughter Lady Sarah Chatto and her family are due to attend, along with a number of other extended family members.
Out of the 22,000 attendees, 10,000 members of the public who won tickets in the public ballot will be present. More than 7,500 tickets were reserved for key workers, members of the armed forces, volunteers, and charities.