These two manuscripts, Add. MSS. 45,319A and B, contain Morris's journal entries for 1871. They were later fair copied for Georgiana Burne-Jones and this copy was used for the Collected Works edition.
The manuscript of these copies is in the Fitzwilliam Museum Library, signed "fair copy . . . made by him for my Mother Georgiana Burne-Jones, and now given by her son and daughter to the Fitzwilliam Museum. / Philip Burne-Jones, July 1922." There are a few differences between Morris's version, available here, and the one which was eventually published.