Which book by J.R.R. Tolkien was illustrated and written as a Father Christmas letter collection?

The Father Christmas Letters is J.R.R. Tolkien’s illustrated collection of letters written in the voice of Father Christmas.

Tolkien created the letters for his children between 1920 and 1943. Each Christmas, he wrote to them as Father Christmas, describing life at the North Pole, mishaps involving helpers, and adventures featuring the Polar Bear. He also supplied drawings, maps, and handwriting designed to make the fictional correspondence feel authentic.

The letters were assembled and edited by Tolkien’s youngest child, Priscilla Tolkien, and published posthumously in 1976. The book preserves both the stories and much of the visual presentation that Tolkien created for his family.

The work is separate from Middle-earth, although it displays Tolkien’s interest in invented languages, maps, mythology, and carefully constructed fictional documents. It is also different from Roverandom and Mr. Bliss, which were other illustrated stories written for his children.