Meghan Markle and Kate Middleton's first official joint engagement - see all the pictures

Meghan Markle made her official debut alongside fiancé Prince Harry and future in-laws the Duke and Duchess of Cambridge in their first public engagement as a foursome on Wednesday. The American actress and the royals set out their charitable vision for the future as they spoke about their Royal Foundation and how it has developed over the years. The event was themed 'Making a Difference Together', designed to showcase programmes run by The Royal Foundation, including causes close to the young royals' hearts, such as Heads Together and the Invictus Games.

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William opened the event, held in the City of London, by outlining the philosophy behind the Foundation, saying: "We would not seek quick wins, but would strive to make a real and lasting difference."

Kate and Meghan seem to have already developed a close bond, and looked especially friendly with one another. Meghan and the Duchess both wore blue, with the American star opting for a navy Jason Wu outfit and the pregnant royal in a soft blue Seraphine number.

Speaking at the event, Meghan revealed she wanted to "hit the ground running" after her wedding by championing women's rights. She told the audience: "I hear a lot of people speaking about girls' empowerment and women's empowerment - you will hear people saying they are helping women find their voices. I fundamentally disagree with that because women don't need to find their voices, they need to be empowered to use them and people need to be urged to listen."

Voicing her support for the #MeToo and #TimesUp campaigns, the 36-year-old added: "Right now, with so many campaigns like MeToo and TimesUp, there's no better time to continue to shine a light on women feeling empowered and people supporting them."

This is the first time the foursome have been pictured together since they attended a Christmas Day church service in Norfolk with the majority of the royal family.

Meghan also said the four of them brought their own perspectives to issues: "Thank goodness (there are) such differing personalities and everyone's very communicative because that's how you can really see bigger change - if everyone's thinking the same way how are you going to push the envelope, how are you really going to break through in a different sort of mindset?"

Prince Harry said that having Meghan join the Royal Foundation would be a much welcome addition, adding: "I think it's really good we've got four different personalities, we've all got that same passion to want to make a difference but different opinions." He added: "And I think those opinions work really really well. Working as family does have its challenges of course it does... the fact everyone is laughing means you know exactly (what I mean) - but we're stuck together for the rest of our lives."

Both Meghan and Kate are clearly at ease with one another, as the foursome shared a joke on stage.

Kate said she had "learnt so much" from her work in parenting and early intervention in mental health. She said: "You can't help but reflect on your own life and it's definitely had an impact on how sort of I look at how I mother, how we work as a family and you know, how we hope to bring up our children."

Harry and Meghan have previously spoken about how Prince William and Kate have warmly welcomed Meghan into the family. Chatting in their first televised interview as an engaged couple, Prince Harry said: "I'd been seeing her for a period of time when I literally didn't tell anybody at all. And then William was longing to meet her and so was Catherine. So, you know, being our neighbours we managed to get that in a couple of - well quite a few times now and Catherine has been absolutely… amazing as has William as well, you know, fantastic support."

William credited Kate with coming up with the idea of launching a campaign. He said: "Catherine was the one who joined the dots together for all of us. She was the one who came up with the idea and the concept as it were. Because Harry and I had never thought of doing a campaign as such before. When you tackle mental health, it was very difficult to know where to start. It's such a big issue and it's so entrenched in society in a negative way sadly, that we weren't quite sure how we would do it and how long it would take."

The Duke also told the forum that the Royal Foundation has an ambitious plan to join up with other major foundations around the world in a bid to make an even greater difference.

The Forum was hosted by BBC presenter and Radio 1 newsreader Tina Daheley who asked Ms Markle for her thoughts on the Royal Foundation. She replied: "To see the model of the foundation is really interesting because, while I've worked with larger NGOs, I've also worked with really small grassroots organisations where you can see a higher level of impact in my opinion, because there's a lot less red tape."

The actress is committed to gender equality and empowering women through her work as a women's advocate for the UN. In 2015, the then UN secretary general Bahn-Ki Moon joined a standing ovation for Ms Markle after she made a speech on International Women's Day as UN Women's Advocate for Women's Leadership & PoliticalParticipation.

Harry said that having Meghan join the Royal Foundation would be a much welcome addition, adding: "I think it's really good we've got four different personalities, we've all got that same passion to want to make a difference, but different opinions."

The Duke and Duchess, who are gearing up for the arrival of their third child in April, looked happy as they waved from inside their car.