The wife of Prince William reportedly went against protocol and opted to "stay in the background" following pleas from animal rights organisations to step out of the Sandringham Estate celebration.
"At the moment Kate is very much the bright new star of the Royal Family and the Palace is keen for her to keep her nose clean," a source told the Daily Star. "Activists have begged her not to join the shoot. No-one wants to see her caught up in a scandal so soon."
Middleton's move has been commended by a number of charity representatives, with the League Against Cruel Sports commenting: "We are pleased that Kate has decided not to take part in the annual bloodbath."
PETA further praised the Duchess of Cambridge for continuing the anti-bloodsport sentiments held by her late mother-in-law Princess Diana.
"The Royals have always had a hard time adjusting to social value," president Ingrid Newkirk commented. "Rather than emulating Diana the Huntress, perhaps the British public is seeing a new Kate who is taking after Diana, the Princess of Hearts."
Prince Philip was absent from the Boxing Day shoot due to his hospitalisation for a blocked coronary artery. He was discharged this morning (December 27) after recovering from heart surgery.