The Duke and Duchess of Cambridge walked hand-in-hand with others to St Mary Magdalene Church from the nearby Sandringham estate in Norfolk yesterday.
As the pair stopped to chat to some of the 2,000 people who had gathered, William explained that the youngster had been left behind in the nursery because of the chilly temperatures. The Duchess of Cornwall, who is suffering from a bad back, was also unable to attend.
Kim Dawson, 43, from Downham Market, came to see the Royals with her mother, Elise Dawson, 83, from Bedford.
William stopped to chat to the pair and the 43-year-old said the Duke told her Prince George was doing “really, really well”.
Ms Dawson said: “They were looking forward to going back to see what destruction he’s created - George was having a lovely day.”
Kate, who is five months pregnant, later apologised to a mother and daughter for failing to bring the one-year-old.
As the Royal Family attended the service, the Archbishop of York delivered a message to the nation which highlighted the importance of tackling isolation at Christmas time.
Dr John Sentamu’s Tweet read: “In the West, one of the greatest problems is loneliness.
“People die alone: poverty of the spirit.”