The Duchess of Cambridge was joined by Prince William and members of the royal family as she hosted a special Christmas carol service at Westminster Abbey.
Kate was supported by the Countess of Wessex, Princess Beatrice and Edoardo Mapelli Mozzi, Mike and Zara Tindall, and Princess Eugenie.
The Duchess' family, including her parents Carole and Michael Middleton, and her siblings, were also spotted arriving at the Abbey.
The Together At Christmas carol service was hosted and spearheaded by the Duchess, and supported by The Royal Foundation, to pay tribute to the incredible work of individuals and organisations across the UK who have supported their communities through the COVID-19 pandemic.
The event featured carols sung by the Westminster Abbey choir alongside Leona Lewis and Ellie Goulding – who performed at the Cambridges' wedding reception in 2011.
The service also included readings delivered by the Duke of Cambridge, British Paralympian and junior doctor Kim Daybell and Good Morning Britain's Kate Garraway.
Royal fans will be able to watch the Christmas concert when it is televised by ITV on Christmas Eve at 7.30pm.
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The Duchess looked festive in a red Catherine Walker dress with matching Gianvito Rossi heels.
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The Duchess was also loaned the Queen Mother's sapphire and diamond earrings, first borrowed in 2015. She brought back a red Miu Miu clutch bag from her royal tour of Canada in 2016.
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In a moving message, Kate wrote how the pandemic showed the "importance of simply being together".
She spoke about "how powerful human connection is to us all" and reflected on the "countless and previously unimaginable challenges" of the Covid-19 crisis.
She described the "heart-wrenching isolation from those we hold most dear" in the programme booklet for her special service.
The Duchess, who hosted the celebratory event, said: "We have lost loved ones, seen our frontline workers placed under immeasurable pressure, and we have experienced heart-wrenching isolation from those we hold most dear.
"Alongside this, we have seen how communities have come together to support those most in need.
"And through our separation from others, we have been reminded just how powerful human connection is to us all.
"Just how much we need one another. And how loving and feeling a sense of belonging to one another can provide comfort in tough times. The importance of simply being together."
The Countess of Wessex was among the members of the royal family in attendance. Sophie cut an elegant figure in a green satin blouse, white high-waisted trosuers and a burgundy corduroy coat from Victoria Beckham.
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Sophie kept her makeup natural with a pop of colour on her lips and highlighter on her freckles. She wore her blonde locks in an updo and added a pendant-style necklace.
Prince William's cousin, Zara Tindall, made a rare appearance at a royal event, alongside husband Mike.
The equestrian wrapped up against the December chill in a navy boucle coat.
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Mike and Zara became parents for the third time in March this year, with the birth of their son Lucas.
The couple held a joint christening for their son in Windsor last month, alongside Princess Eugenie and Jack Brooksbank's son, August.
Princess Beatrice and Edoardo Mapelli Mozzi made quite the stylish entrance together at Westminster Abbey. The couple enjoyed a date night just months after welcoming daughter Sienna in September.
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New mum Beatrice wore her auburn locks in loose curls and accessorised with a satin burgundy headband.
Princess Eugenie looked gorgeous in a caped green coat and knee-high boots for the concert.
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The Duchess of Cambridge's family turned out in support, including mother Carole Middleton, brother James and his wife Alizée.
Carole sported a berry hued coat while Alizée wore a printed suit with a white turtleneck knit.
Kate's younger sister, Pippa, led the Middletons into the Abbey, wearing a forest green coat. Pippa and her husband, James Matthews, welcomed their second child, Grace, in March.
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Kate's father, Michael Middleton, joined his wife and youngest children.
Kate Garraway looked lovely in a red knitted dress and oxblood boots as she arrrived for the special service.
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William and Kate could be seen catching up with Mike and Zara Tindall, and Princess Eugenie, ahead of the concert.
The Duchess' proud family look on as they take their seats in the second row.
The Duchess was reunited with six-year-old Mila Sneddon, who stole the royal's heart after she bravely coped with leukaemia during the pandemic.
The youngster gave Kate a twirl in her green sequinned dress before taking her seat behind the royals.
Mila said afterwards: "She asked me what I was getting from Father Christmas and I told her I wanted a Barbie Dreamhouse.
"I showed her my dress and she said I looked lovely."
Mum Lynda said: "Last two Christmases Mila has been in hospital so we are looking forward to having Mila at home this year. We are just an ordinary family, it is amazing to be invited."
The youngster, from Falkirk, in Scotland, also gave a short reading during the hour-long ceremony.
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The Duke and Duchess were entertained by a choir singing carols as they left Westminster Abbey, and the couple got to meet some real-life reindeer.