Kate's carol service message: You were by my side

Catherine, Princess of Wales is to host her annual Christmas carol service at Westminster Abbey on Friday, her biggest event in her return to royal duties after ending her chemotherapy.

A specially-designed illustration by British artist Charlie Mackesy - which embodies the service's themes of kindness, love and empathy - will feature on the Order of Service.

Families affected by the Southport knife attack will be among the 1,600 guests at the event.

It comes at the end of a difficult year for Catherine, after her cancer diagnosis in March, followed by months of treatment.

The illustration says: "How did I help?" with the answer "you were by my side, which was everything" - expressing the carol concert's message of showing solidarity for those in need.

The children's illustrator, who is is known for his bestselling book The Boy, The Mole, The Fox And The Horse, said: "I hope it reminds us of the beauty of being there for each other at Christmas."

Ahead of the carol concert, Kate sent a letter to guests calling for "love, not fear".

Each stage of Kate's return to the public eye has made headlines, but this week will have seen her at two major events - the emir of Qatar's state visit and this Together at Christmas carol service.

And more than any of the events so far this year, this concert will place the princess centre stage rather than in a supporting role.

This will be her big personal moment - after a year of health worries described by the Prince of Wales as "brutal" for their family.

There will be famous performers at the concert, including Richard E Grant, Paloma Faith, Olivia Dean and Gregory Porter, along with guests who have worked hard to help others in their communities.

It is intended to show support for those who have had tough years, including families of those caught up in the Southport knife attacks, whom the princess visited in October.

Olympic and world-champion cyclist Sir Chris Hoy, who also received a cancer diagnosis this year, will be among those lighting candles.

But much of the focus will be on Catherine, Prince William and other Royal Family members at the service.

The language in the run-up to the carol concert has been strikingly emotional, calling for greater empathy for those facing difficulties.

"Love is the light that can shine bright, even in our darkest times," Catherine wrote in a letter to guests invited to the concert, which is being recorded for an ITV programme on 24 December.

In her letter, Catherine writes about the importance of compassion, "gentle words or a receptive ear, an arm around an exhausted shoulder, or silently being by someone's side", and "the love that we show ourselves and the love we show others - love that listens with empathy, love that is kind and understanding, love that is forgiving, and love that brings joy and hope".

And guests will be able to leave a message on a "kindness tree" outside the abbey.

Whether a reflection of her own experiences of ill health in such a high-profile role, or addressing a social-media generation that expects more emotional openness, it is a very different tone from traditionally understated royal messages.

It has a similarly personal approach to Catherine's video on social media in September, when she announced she had finished her chemotherapy treatment, with its message of hopeful endurance: "Out of darkness, can come light, so let that light shine bright."