According to The Sun newspaper, Prince Harry paid around £8000 for a first edition Winnie-The-Pooh for Louis’ christening.
Pom Harrington, of Peter Harrington Rare Books, said: “Obviously we do not discuss what our customers buy, but first edition children’s books make excellent Christening presents.”
The 1926 first edition by AA Milne, printed by Methuen & Co, could be the first in a library that Prince Harry hopes to put together for his nephew.
Louis, born in April, was christened by the Archbishop of Canterbury Justin Welby on July 9.
Prince Harry is due to visit Ireland today and among the itinerary is a visit to the illuminated manuscript Book of Kells at Trinity College in Dublin.