Kate joined by children as she hosts carol service

The Princess of Wales has hosted her annual Christmas carol service at Westminster Abbey - the biggest event in her return to royal duties after ending her chemotherapy.

It was a candle-lit, festive occasion, but also with some poignancy – as it came 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 were families affected by the Southport knife attack, and a candle was lit by Olympic cyclist Sir Chris Hoy, who had a cancer diagnosis.

The Prince of Wales joined Catherine at the service, along with the couple's three children - Prince George, Prince Louis and Princess Charlotte.

It was an atmospheric occasion in the medieval Abbey, which was richly decorated in winter colours of red and green, with Christmas trees dotted around the ancient tombs and monuments.

"I didn't know this year was going to be the year that I've just had... But lots of people have had challenging times," Catherine said to singer Paloma Faith.

Catherine wore a bright red coat - and when she saw the singer also wearing the same colour, she said: "It's a celebration, everybody's wearing red."

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

The Together at Christmas service was a mix of traditional carols, music and readings, with Catherine looking relaxed and greeting the performers when she arrived at the Abbey.

The Prince of Wales read a lesson from the Bible, and actor Richard E Grant performed a passage from A Christmas Carol by Charles Dickens.

There were songs and carols from Paloma Faith, Olivia Dean and Gregory Porter, in an event that will be broadcast by ITV on Christmas Eve.

Catherine spoke to singer Olivia Dean about her own memories and emotional associations with the Abbey, including being married there.

Many in the congregation had been invited to thank them for their work in helping others in their communities.

They included 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 there was Diven Halai from London, who has a serious lung condition but ran the London Marathon with an oxygen machine, in a charity fundraiser.

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

He's now an ambassador for the Royal British Legion and gives talks to schools about his wartime experiences.

The theme of the service was the importance of kindness and empathy and the congregation heard readings and prayers linking it to the story of Christmas.

Prominently displayed in the nave of the Abbey was a large nativity scene, with figures of Jesus, Mary, Joseph and the shepherds.

Guests received a letter from Catherine, which said that the Christmas message was about promoting "love, not fear".

"Love is the light that can shine bright, even in our darkest times," the princess wrote, at the end of what has been a difficult year for her and her family.

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

The illustration said: "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."