Best photos from Prince Harry and Meghan Markle's London outing

The Duke and Duchess of Sussex have made some non-official appearances in the past week, stepping out for the polo twice, once with their friend Serena Williams. But on Thursday, Harry and Meghan carried out a royal engagement, attending the Your Commonwealth Youth Challenge reception at Marlborough House in London.

The couple were introduced to youngsters from across the Commonwealth, including Australia, New Zealand, Fiji and Tonga – countries that Harry and Meghan will visit on their royal tour later this year. At the reception, Harry, 33, gave a speech. The Duke and Duchess also spoke to the newly elected Commonwealth Youth leaders, who were taking part in a workshop about the future, and their role in shaping it.

It comes a week after Harry and Meghan celebrated the Queen's Young Leaders Awards Ceremony at Buckingham Palace, where young change-makers from across the Commonwealth were presented with awards from the Queen.

Click through to see the best moments from the day…

The Duke and Duchess of Sussex held hands as they arrived at the event, walking alongside Patricia Scotland, Secretary-General of the Commonwealth.

Meghan dressed for the heatwave in a vibrant yellow midi dress. The former actress looked typically stylish in the sleeveless design, which was from US fashion designer Brandon Maxwell. Letting her dress do the talking, Meghan styled it simply with nude heels, Adina Reyter earrings and wore her hair in a low bun.

The Duchess of Sussex reached affectionately for her husband’s arm as they chatted on their arrival at Marlborough House.

Prince Harry addressed the crowd at the reception and said how “excited” he and Meghan are to be working with young people across the Commonwealth. The Duke also urged the group to tackle plastic pollution, saying: “Just in the last year, the world’s understanding of the damage being done by single use plastics has grown rapidly and many governments and communities are taking big steps to tackle this very challenging problem.”

He added: “Whether it’s biodegradable food packaging or limiting plastics use, there are good examples of everyone doing their part and I am sure many of you will play a role in your own communities to identify problems, but better yet, to develop solutions.”

Meghan looked on proudly while Prince Harry gave a speech to the crowd of 120 young people, scholars, youth leaders and youth representatives of High Commissions who had been invited to take part in the ‘Your Commonwealth’ event.

The Duchess was every inch the proud wife, and applauded her husband after he finished his speech.

The Duke and Duchess of Sussex took time to mingle the guests at the reception, as they spoke about the work that is being doing across the Commonwealth by inspirational young people.

Prince Harry and Meghan, along with Patricia Scotland, were entertained by performers at the outside reception in the grounds of Marlborough House.