Kate Middleton steps out for surprise outings in London to mark book publication day - best photos

The Duchess of Cambridge stepped out in London on Friday after teasing royal fans with a fun video on the day of the publication of her Hold Still photography book.

Kate visited The Royal London Hospital and the National Portrait Gallery's Archive, a year to the day since she launched the community project with the Gallery.

READ: Kate Middleton teases royal fans on the day of exciting book launch

WATCH: Kate Middleton visits The Royal London Hospital to see how art is used to help patients

Kate visited the Royal London Hospital in east London to learn how Barts Health NHS Trust's Vital Arts organisation commissions art for the Royal London and the trust's other hospitals to improve the patient and staff experience.

She sat down with a range of staff to chat about their experiences during the pandemic and asked: "How you all doing? I know hospitals are busy places but the extra pressure of Covid… How’s the mood now?"

She was told morale was good and was shown examples of photographs taken by staff from Barts Health NHS Trust to document this period in history.

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Earlier on Friday, the Duchess teased royal fans with a video clip shared on the Cambridges' Instagram account, showing Kate leaving a copy of the book outside Kensington Palace for someone to find.

The Duchess teamed up with The Book Fairies to mark the publication of Hold Still, a literary movement which urges readers to share books which they have read and enjoyed by leaving them in public spaces for others to find. In total, 150 copies of the book have been hidden in secret locations across the UK by the Hold Still judging panel.

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The Duchess also saw Johannah Churchill's framed picture entitled "Melanie, March 2020", an image of her fellow nurse wearing personal protective equipment and helping to prepare a Covid-19 clinic for patients.

The picture was recreated as a powerful mural in Manchester and is the cover image of the book Hold Still.

Kate and the National Portrait Gallery gifted the framed portrait to the Royal London and it will go in display in the hospital's main corridor.

Looking at the portrait, she said: "It's become really iconic, hasn't it?

"Some of them had really powerful stories behind them and this one really stood out.

"I spoke to Johannah and she was so, 'this is not about me, it’s about the people who I represent'. She was so humble about it."

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Kate also viewed the hospital's Vital Arts projects displayed throughout its wards, waiting rooms and corridors to enhance the environment. 

The Duchess stopped by one colourful print by artist Kate Brice and was told it was made with ink and glitter.

"Charlotte would love that one," she said of her six-year-old daughter.

Kate then laughed as picked up a book by Chris Haughton called Oh No, George!

She said: "That’s very appropriate," and was later given it as a gift for her son.

The Duchess stepped out in a red Eponine coat from the brand's AW18 collection and a camel pleated skirt for her engagements in London. 

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Kate then visited the National Portrait Gallery's Archive, where Nicholas Cullinan, Director of the NPG, confirmed that the final 100 Hold Still images will become part of the Gallery's national Collection, ensuring that this unique collective portrait of an extraordinary period in the  nation’s history is conserved for future generations

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Kate also met Hold Still entrants, Naz Maleknia (centre) and Claudia Burton, whose photographs feature in the book. 

She told them: "These are personal moments you have captured, and it's a great thing to share them with the world."

The Hold Still book has been put together with support from The Co-op, which helped run the community exhibitions on billboards and outdoor poster sites in 80 towns, cities and areas last October. The final 100 images were first displayed in a digital exhibition on the National Portrait Gallery's website.

Net proceeds raised from the sale of the book will be split between leading mental health charity Mind, and the National Portrait Gallery. The funds will help to support arts and mental health projects across the UK, including Mind's work in local communities and the National Portrait Gallery's education and community projects.