The Duke and Duchess of Cambridge, Prince Harry and Meghan Markle are attending their first annual Royal Foundation forum in London.

The event is the two royal couples' first official engagement together.

Launched in 2011, the foundation was set up by the royal brothers to pursue their charitable and philanthropic interests.

William, Kate and Harry - the foundation's three joint patrons - will talk about the charitable body that has allowed them to launch a range of projects supporting wounded military veterans, protecting wildlife and promoting good mental health.

Opening the event, Prince William outlined the philosophy behind the Foundation, saying: "We would not seek quick wins, but would strive to make a real and lasting difference."

The duke said they took inspiration from their parents the Prince and Princess of Wales who were "an example of diligence, compassion and duty".

He also referenced their grandparents, the Queen and Duke of Edinburgh, who "had made support for charity central to their decades of service to the nation and the Commonwealth".

Prince William said he and his brother were inspired by their parents. Credit: PA

William told guests, who included foundation supporters, programme partners and beneficiaries: "The task for us would not be to reinvent the wheel.

"Instead, our job was to follow the example of those who had come before us, hold on to the values that have always guided our family, but seek to engage in public life in a way that was updated and relevant for our generation.

The Duke highlighted the various projects which were spearheaded under their organisation from the Invictus Games, which has used a sporting championship to aid the rehab of wounded and injured military and veterans, to the Heads Together campaign which challenged the nation to talk about their mental health.

Meghan and Kate pictured smiling during the event. Credit: PA

Ms Markle has already been named as the fourth patron of the foundation and will officially join William, Kate and Harry as the latest figurehead of the organisation when she marries the prince on May 19.

Harry said Meghan 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.

Ms Markle added: "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?"

The two couples previously appeared together for the first time at the Christmas Day service at the Queen's Sandringham estate.