Her Royal Highness has organised her yearly Christmas carol concert at the iconic London venue, with a congregation comprising dignitaries, stars, and everyday helpers who have helped their communities.
The large audience will hear a mix of carols, music and readings from actors such as award-winning actors.
The focus of the event, held in the atmospheric historic church on Friday afternoon, is compassion and demonstrating care for others.
Among the guests will be Jonathan and Anna Cordiner, whose daughter died of a brain cancer, and who set up a charity, a charity called Kayleigh's Wee Stars, to help households where there is a child with a terminal illness.
"The dedication, empathy, and kindness you show, often without fanfare or recognition, and without any expectation or recognition, make an extraordinary difference to the well-being of people," the Princess expressed in a message before the concert.
The royal has been undertaking her own measured re-emergence to the public eye subsequent to her illness and medical care, recently giving her initial major address in two years, in which she talked about recognising the "quiet, often invisible work of caring".
Attendees entering the Abbey will enjoy performances from young musicians backed by the charitable trust Future Talent, established in part by the former royal to broaden opportunities for music lessons.
An 18-year-old named Carys Wood, who is a trumpet player and is from Wales, has been helped by the charity, with awards contributing to musical instruments, lessons and travel costs - and she said it was "incredible" to be performing at the concert.
"Pursuing music is often costly," she stated. She is now studying at the Royal Academy of Music, and added that "all people deserve the chance" to hone their artistic talents.
Carys's 11-year-old sister, Eliza, who is a euphonium player, will be present at the Abbey. "I never imagined I would perform in front of so many distinguished guests," she said.
Within the audience will be people from various age groups.
That will feature nine-year-old Saphia Turner, recipient of a prize for youthful altruism, who creates and sells art and completes fundraising tasks to collect donations for local food charities.
The Abbey has been adorned with custom-created holiday decorations, with well-known chef Mary Berry and flower expert Simon Lycett helping to make them.
Among the musical performers will be singer Katie Melua, the Abbey's own choir and a Cornish sea shanty group, the group Fisherman's Friends, who said the chance to take part was "the perfect culmination."
The festive event titled 'Together at Christmas' will be aired by a major network on Christmas Eve.
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