The Princess of Wales is hosting her customary Christmas carol concert at the historic Abbey, with a congregation comprising royals, celebrities and local heroes who have made a difference in their neighbourhoods.
The 1,600 guests will enjoy a selection of carols, music and readings from performers including award-winning actors.
The central message of the event, held in the candle-lit Abbey on the afternoon, is generosity and expressing affection towards one's neighbour.
Attending the event are a couple named the Cordiners, whose daughter died of a brain tumour, and who founded an organisation, Kayleigh's Wee Stars, to help households where there is a terminally ill child.
"The time, care and compassion you give, often discreetly and without words, and without any expectation or recognition, make an remarkable change to the circumstances of individuals," Her Royal Highness stated in a letter ahead of the festive gathering.
The royal has been undertaking her own steady comeback to public life subsequent to her illness and medical care, in November making her initial major address in two years, in which she talked about recognising the "selfless, commonly overlooked efforts of carers".
Attendees entering the Abbey can listen to young musicians aided by the charitable trust Future Talent, set up with the help of the former royal to broaden opportunities for musical tuition.
Carys Wood, aged 18, who plays the trumpet and is from Pembrokeshire, has been supported by the charity, with awards contributing to equipment, teaching, and travel fees - and she said it was "amazing" to be taking part in the concert.
"Pursuing music is often costly," she stated. She is now enrolled at the Royal Academy of Music, and added that "all people deserve the chance" to develop their musical skills.
Eliza, Carys's sister who is 11, who plays the euphonium, will likewise attend the Abbey. "I never thought I'd be able to play there in front of so many notable figures," she said.
Among the guests will be people from various age groups.
That will encompass nine-year-old Saphia Turner, winner of a young hero award, who creates and sells art and completes fundraising tasks to raise money for community pantries.
The Abbey has been festooned with specially made wreaths, with celebrity baker Mary Berry and floral designer Simon Lycett helping to make them.
The musical lineup includes recording artist Katie Melua, the Westminster Abbey choristers and a Cornish sea shanty group, the group Fisherman's Friends, who said the invitation to sing was "a dream come true."
This annual carol service will be broadcast on ITV1 on Christmas Eve.
