The Princess of Wales is hosting her annual Christmas carol service at Westminster Abbey on Friday – the biggest event in her return to royal duties after ending her chemotherapy.

It is a candle-lit, festive occasion, but also with some poignancy – as it comes at the end of a year of health problems for Catherine and for some of the guests who have faced very difficult times.

Among the 1,600 guests are families affected by the Southport knife attack, and a candle will be lit by Olympic cyclist Sir Chris Hoy, who had a cancer diagnosis.

Also attending the service is the Prince of Wales as well as their three children, Prince George, Prince Louis and Princess Charlotte.

The Prince of Wales will deliver a Bible reading, and actor Richard E Grant will read a passage from A Christmas Carol by Charles Dickens.

Prince George and Prince Louis were both seen wearing red ties to match their mother’s red coat.

Performers at the Together at Christmas service will include Paloma Faith, Olivia Dean and Gregory Porter, along with guests who have worked hard to help others in their communities.

They include 18-year-old Olivia Bowditch from Dorset, who volunteers for a charity that sends letters to cancer patients at risk of being lonely and isolated.

Also at the carol service will be Diven Halai from London, who has a serious lung condition but ran the London Marathon with an oxygen machine, in a charity fundraiser.

There will be five World War Two veterans attending, including Bernard Morgan from Crewe, aged 100, who landed in Normandy on D-Day.

Lord Frederick Windsor, his wife Sophie Winkleman and their two daughters also attended the service.

Other royal guests included the Duchess of Edinburgh, Princess Beatrice and the Duke and Duchess of Gloucester.

The Abbey, decorated with Christmas trees from Windsor Great Park, will host a service with traditional carols, music, readings and prayers, emphasising the importance of compassion and kindness.

Catherine has written a letter to guests saying the Christmas message is about promoting “love, not fear”.

“Love is the light that can shine bright, even in our darkest times,” writes the princess.

The Order of Service sends the same message of empathy, with a specially commissioned illustration by Charlie Mackesy.

The illustration says: “How did I help?” with the answer: “You were by my side, which was everything”. This sentiment expresses the carol concert’s message of showing solidarity for those in need.

Prince William has also been helping others this week, with a visit to the Passage homelessness charity in Westminster.

The prince, who has been associated with the charity since going there first with his mother Diana, helped prepare the Christmas dinner for the charity’s clients.

Leo Scanlon, who was at the dinner, praised the prince for how he talked to people and for the questions he asked: “He clearly has a great understanding of homelessness and the issues around it.”

The prince has described this year as having been “brutal” for his family, and the focus of attention at the carol service will be on his wife Catherine, as she continues her recovery after ending chemotherapy.

Each stage of her return to public life has made headlines, but this week will have seen her at two major events – the Emir of Qatar’s state visit and this carol service.

More than any of the events so far this year, this concert will place the princess centre-stage rather than in a supporting role. It will be her big personal moment.