Kate and William reveal poignant Christmas card

The Christmas card image was from a video released by Catherine earlier this year

The Prince and Princess of Wales have revealed a Christmas card with a personal significance, using a picture taken from the video released when Catherine announced the end of her chemotherapy.

The emotional video, with its emphasis on family and supporting each other in difficult times, was filmed in Norfolk in August.

The personal video from Catherine, at the end of treatment after her cancer diagnosis, had the message "out of darkness can come light".

The image used for this year's card, by film maker Will Warr, shows Prince William and Catherine and their children Prince George, Princess Charlotte and Prince Louis.

The card, with its very personal connections to a difficult year for the couple, has already been sent out in the post, but has now been revealed on social media.

The card includes the message "Wishing you a Happy Christmas and New Year".

Catherine has been making a gradual return to public duties following her cancer treatment.

She went to meet the families of those bereaved in the Southport knife attack in October and some of those families were among the guests at Catherine's Christmas carol service, which she hosted this month in Westminster Abbey.

Prince William said this has been a "brutal" time for their family and described the past year as the "hardest year" of his life.

The video by Will Warr, used for the Christmas card, was seen as a strikingly different approach to releasing a royal message.

It was a health update in September that explained that Catherine had completed her chemotherapy, but it had a much more personal style and an unashamedly emotional message.

"Life as you know it can change in an instant and we have had to find a way to navigate the stormy waters and road unknown," she said, in a voiceover to the video, which showed pictures of the family in the Norfolk countryside.

It was a tone that continued into a letter sent to guests for her carol concert, which called for "love, not fear".

The Prince and Princess of Wales are already in Sandringham in Norfolk for Christmas and so have missed the traditional pre-Christmas royal gathering at Buckingham Palace on Thursday.

It was revealed on Wednesday that the Duke and Duchess of York would not attend the lunch for the extended Royal Family, in the wake of the controversy over the duke's contacts with an alleged Chinese spy.

This year's Christmas card from Prince William and Catherine follows in their style of informal and relaxed family images, without any traditional royal imagery.

Last year they were seen in a rather arty black and white picture, showing them together as a family, but also with a style that owed something to an upmarket jeans advert.

This year's card from King Charles and Queen Camilla shows them in a cheerful outdoors image, taken soon after the King had heard that he would be well enough to return to his public duties.

Prince Harry and Meghan's "Happy Holiday Season" card this year included an appearance by the couple's two children.