In keeping with her regal style, the 87-year-old reigning monarch wore a smart cream suit with beading, a matching hat featuring feathers and a chic diamond brooch. A pair of pearl earrings and white gloves finished off the royal outfit.
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Her husband Philip, 92, appeared to be in fine health after a recent bout of illness. The Duke was smart in a dark suit and a navy tie, as he was seen smiling with his hands joined as he listened to a welcome address at the beginning of their visit.
Prince Edward, meanwhile, who joined his parents for the visit, was seen warmly greeting his mother with a kiss. The trio sat together at the event, with Prince Philip in the middle.
Teamwork came into play when the Queen and Prince Philip unveiled two plaques to commemorate their visit to the Royal Commonwealth Society in Westminster.
Prince Edward accompanied his parents on the public outing just days after celebrating his milestone 50th birthday on Monday, when the royal family attended a service at Westminster Abbey for the Observance of Commonwealth Day.
Dressed in a bright coral outfit with a matching hat, the Queen and head of the Commonwealth was all smiles as she was accompanied by her husband Prince Philip.
The royal couple were greeted at the entrance by the Dean of Westminster John Hall and Sub-Dean and Archdeacon Jane Hedges. Before the start of the service, the Queen broke the flag in a traditional ritual.
Prince Charles and his wife Camilla, Duchess of Cornwall, and birthday boy Prince Edward and his beautiful wife Sophie, Countess of Wessex, were also in attendance.