A book on the making of the Treaty of Versaille, by a person who was a contributing party to English delegation :
Harold Nicolson
Peacemaking, 1919
blurb:
This book was first published January 1st 1933. And just as a bit of gossip, 'Sir Harold George Nicolson KCVO CMG was an English diplomat, author, diarist and politician. He was the husband of writer Vita Sackville-West, their unusual relationship being described in their son's book, Portrait of a Marriage.' (Copied from the Goodreads description of him)