The Princess of Wales quietly carried out a joint engagement with the Prince of Wales on Wednesday, after pulling out of attending Royal Ascot last week.
According to the Court Circular, Prince William and Kate received Melinda French Gates at Windsor Castle.
The American philanthropist is the founder of Pivotal Ventures, an organisation which aims to advance equality and give opportunities to women across the US.
The Prince and Princess represented their Royal Foundation at the meeting, which focuses on areas including the early years and mental health.
The engagement took place behind closed doors with no photographs released. Earlier in the day, William hosted an investiture at Windsor Castle, where he awarded former England manager, Sir Gareth Southgate, with his knighthood.
© Alamy Stock PhotoKate, 43, missed Royal Ascot last week as she continues to find the right balance after cancer treatment.
According to The Daily Mail, the Princess will not be seen publicly this week, but she is expected to attend Wimbledon in the coming weeks, which starts on Monday 30 June.
© Getty ImagesThe Princess will also reportedly be involved as French President Emmanual Macron and First Lady Brigitte Macron are hosted for a state visit at Windsor Castle from 8 to 10 July. However, it's not known if Kate will attend the white-tie state banquet.
Last Friday, the Princess released a personal message in support of Children's Hospice Week.
Kate praised the "extraordinary work" of children's hospices for "lifting spirits through laughter, fun and play, as well as listening, holding, caring and sharing".
The royal is patron of East Anglia Children's Hospices (EACH) and Tŷ Hafan Children's Hospice in South Wales.
Prince William's week
Meanwhile, the Prince of Wales attended a panel discussion at the Leading with Impact event on Tuesday to mark London Climate Action Week.
William also confirmed that he will travel to Rio de Janeiro for the fifth Earthshot Prize Awards in November.
© Getty ImagesHe said: "From a personal point of view, I've always wanted to get South America, particularly Brazil. So I'm personally very excited about going down there. I think South America as a whole, the amount of ecosystem, kind of environmental interest and passion that is there.
"I think that's really important. And I think they epitomise the approach to what we can be doing more sustainably. The vibrancy, the energy, the enthusiasm. I think the awards will be spectacular."
The Earthshot Prize, founded by the Prince in 2020, aims to find solutions to "repair" the planet.
