The brief note, which was given to the second-in-line to the throne over the holidays, reads: "William, I hope you enjoy opening this each day" and was written on Buckingham Palace stationary. The gift is thought to have been an advent calendar.
Executive VP of RR Auction in Boston has spoken about the rare item, which has been listed to sell at around $2370 (£1400), calling it: "A seldom-encountered piece of correspondence from within the royal family, enhanced by its fitting Christmas time association."
Other items to be auctioned include a portrait photograph of King George VI and the then-Queen Elizabeth with their daughters, Princess Margaret and Princess Elizabeth, and a Christmas card signed by the two Princesses from 1946 as well as an early portrait of her Majesty sitting by herself.
A fifth item to be auctioned is a detailed letter from the then 24-year-old Prince Edward who later became King Edward VIII. The letter, signed simply 'Edward', was sent to a Captain Faussett, and an excerpt of the lengthy correspondence reads: "Ever so many thanks for your kind letter & good wishes for my birthday; it was very nice of you to write!! We had quite a stiff 24 hour battle three weeks ago when the Austrians attacked us though.
"My visit to Rome was semi-official 'on duty' & it was one long string of official visits, meals, receptions, etc & I had to make a speech in a place like the Albert Hall one night & I also visited the Pope… Oh!! This war how it does drag on though. It's going to last another 10 years, that's what I feel about it though. Of course the Americans are going to pull us through we should be done without them!! Please forgive such a rotten, dull & untidy scrawl but it's written in the office where we are very busy & where I’m being interrupted the whole time! (sic)"