As dark and heavy as plum pudding

Dressed up as a child-friendly, pocket-sized hardback, just the right size for a Christmas stocking and with a pretty front-cover illustration of two dear little children in a snowy fir forest, Inventing the Christmas Tree (Yale, £12.99) is actually a learned 90-page thesis on the history of the Christmas tree by the German author Bernd Brunner, who has also written monographs on bears, the moon and snowmen.