Both Kate and William donned blue for the occasion, and their appearance came hours after they met with photographers near Waterloo earlier in the day.
WATCH: Prince William and Kate Middleton meet finalists from the Hold Still photography project
In the photos, the Duchess could be seen in a beautifully tailored blue suit, while the Duke opted for one in an almost identical shade. Kate wore a gorgeous floral dress and could be seen chatting away to the doting parents as they filmed for the Pride of Britain awards outside St. Bartholomew's Hospital in the capital.
Kate and William out in London on Tuesday
Kate launched the Hold Still campaign in May in collaboration with the National Portrait Gallery, of which she is patron. She helped to select 100 finalists from 31,000 entries and unveiled them in the National Portrait Gallery’s digital exhibition in September.
The campaign celebrates the poignant moments experienced throughout lockdown, and will no doubt be close to journalist Kate's heart. The doting mum's husband Derek remains in hospital after contracting the virus earlier this year.
Also on Tuesday, Kate was visibly moved after speaking to former Prime Minister Gordon Brown on GMB. Discussing the impact the pandemic may have on young people's jobs in the future, the politician made reference to Kate's family situation as the interview came to an end.
"And our thoughts are always with Kate and her family," he said, to which Kate replied: "Well, thank you very much."
Gordon and Derek, who was formerly a member of the Labour party, had worked together in the past.
The royal couple delighted fans earlier in the day when they met some of the 100 finalists of the Hold Still project which documented life in the UK during lockdown.
As the striking images of life during lockdown go on display in 80 towns and cities across the UK, William and Kate donned facemasks and headed to Waterloo to meet Hackey Food Hub volunteer Sami Massalami Mohammed Elmassalami Ayed, who featured in the image "Sami", taken by Grey Hutton.
The Duchess looked lovely in red
They also visited St Bart's Hospital to meet Joyce Duah, who took the photograph "All in this Together." Joyce, who is a specialist oncology pharmacist, photographed colleagues Amelia Chowdhury and Dipal Samuel, who were drafted in to work as pharmacy technicians in the Intensive Care Unit.
Speaking about Joyce's work, the Duchess said: "Thank you so much for the image. It had such an impact it captured the moment, it was a look behind the scenes. The story of what you experienced is so important."
The Duke added: "It is important for history purposes to show that actually happened."
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