The Princess of Wales was among the senior members of the royal family at a Buckingham Palace reception on Saturday afternoon.
Kate, 40, joined her husband, Prince William, as well as King Charles, Queen Consort Camilla, the Earl and Countess of Wessex, the Princess Royal and Vice Admiral Sir Timothy Laurence for a lunch with governors-general from the Commonwealth realms on Saturday.
The princess, who was dressed in a black A-line dress and accessorised with a pearl necklace, was pictured chatting with the Queen Consort.
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At one stage, Kate, who was wearing a long three-strand pearl necklace, placed her hand on the arm of Saint Lucia governor-general Cyril Errol Melchiades Charles as they spoke.
The princess also stood next to the King as he conversed with the dignitaries, with William also mingling in the busy room.
The princess was pictured in conversation with the Queen Consort
In addition to the UK, the King is head of state for 14 Commonwealth realms.
These are Antigua and Barbuda, Australia, The Bahamas, Belize, Canada, Grenada, Jamaica, New Zealand, Papua New Guinea, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Solomon Islands, and Tuvalu.
Kate with Saint Lucia governor-general Cyril Errol Melchiades Charles
William and Kate's latest appearance comes after the couple visited Army Training Centre Pirbright in Surrey on Friday afternoon where they spoke with Commonwealth troops participating in the procession on Monday.
Earlier on Saturday, the prince joined the king to greet the crowds waiting in the queue for the Queen's lying in state at Westminster Hall.
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The princess and the king pictured during the reception
Charles and William stopped for an impromptu walkabout in Lambeth following their visit to the Metropolitan Police Service Special Operations Room, where they thanked emergency service staff for their work during the mourning period and ahead of the Queen’s funeral on Monday.
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