I have got both volume I and II of this catalog, both originals. No letters or other documents are enclosed. Are the letters bound in or just stored in the book by a previous ownder? What are these letters about, can you post photo's?
So the books were sent as a gift to the first owner by the Deputy Master (William Ellison-Macartney). I do not think all copies were distribited this way as the price is neatly printed on the front leaf. My copies state 10 shillings in Volume I and 6 shillings in Volume II.
From Wikipedia: William John Hocking CVO CBE (10 March 1864 - 10 April 1953) was a British numismatist. He worked at The Royal Mint from 1883 to 1926, beginning as a clerk and retiring as Superintendent of the Mint. At the time the books were published he was the librarian and curator of the Mint's collection of British coins.