Kate attends Christmas carol service - as Louis leaves message for grandparents

Kate, 42, was joined by her family, including the Prince of Wales, 42, and their children George, 11, Charlotte, nine, and Louis, six.

William and the royal children arrived after visiting the "kindness tree" by the abbey's great west door and hung messages on its branches dedicated to someone who had supported them in their lives in keeping with the service's theme of love and empathy.

They all arrived clutching their red tags and Louis' could be seen with the handwritten words: "Thank you to granny and grandpa because they have played games with me."

Kate was pictured welcoming her guests and talking to attendees, all 1,600 of whom received their invites as they had supported others in some way.

The princess, who has been hosting the Together at Christmas Carol service for the past four years, announced last month she had completed chemotherapy treatment for an undisclosed form of cancer.

She added: "But I think lots of people this year have had such challenging times, many who are here today."

The princess then thanked the singer for agreeing to perform at the service and said: "I know as a mum it's hard pulling yourself away, the juggling."

The princess then went on to share a sweet anecdote about her youngest child, Louis, who she said had been desperate to tell his sister about dancers performing during the event.

"I said 'Louis can you keep a secret because I want it to be a surprise for Charlotte', who loves her ballet, and he said 'promise, promise I won't say anything', and he's kept the secret."

But as she did the school drop off this morning, Kate said he asked: "Mummy please can I tell her, I'm bursting."

The princess added she hoped he managed to keep the secret.

In a message sent ahead of the service, Kate said Christmas is a moment of "celebration and joy" as well as an "opportunity to slow down and reflect on the deeper things that connect us all".

She added: "Christmas is one of my favourite times of the year."

In November, she joined other senior royals for Remembrance Day services, while in October she made a surprise visit to the families of the victims of the Southport attack.

In her letter to the carol-goers, Kate seemed to hint toward the struggles the Royal Family has faced over the past year, with the King also being diagnosed with cancer.

"Love is the light that can shine bright, even in our darkest times," she wrote.

Prince William recently described the past year as "brutal" and probably "the hardest year in my life".

Olympic cycling champion Sir Chris Hoy, who is terminally ill with prostate cancer, lit a candle as did Lindsey Burrow, the wife of former Rugby League star Rob Burrow who died in June with motor neurone disease.

The event will be broadcast as part of the programme Royal Carols: Together At Christmas, screened on ITV1 and ITVX on Christmas Eve, and it will feature three films about the stories of people and organisations who have inspired, counselled and comforted others in their times of need.

-SKY NEWS