Papers of and relating to Evelyn Underhill, 1874-1997 and undated, comprising personal correspondence of and concerning Underhill, 1888-1969 and undated, the correspondents including Baron Friedrich von Hugel (three letters, 1911-1916), Underhill's husband Hubert Stuart Moore (117 letters from Underhill to Moore, 1890-1912 and undated, and 30 letters from Moore to Underhill, 1898-1906 and undated), Rabindranath Tagore (typed transcripts of 10 letters from Underhill to Tagore, 1913-1914), and members of the Underhill family, the subjects ranging from Catholicism, travels in Italy, Switzerland and France, publications and lectures, spiritual matters and advice, mysticism, health, and World War Two; correspondence, 1907-[1954], with various publishers concerning Underhill's publications (some posthumous) and broadcasts, including copyright, costs, sales and royalties; manuscripts and typescripts containing proposed holiday itineraries and recording Underhill's impressions while travelling in Italy, Switzerland and France, 1898-1899, 1901-1907; poetry, 1917-1923 and undated, including some work which was published; a speech at King's College London on being elected a Fellow, 1927; an article on 'The Fountain of Life: an iconographical study', published in 1910; material relating to spiritual development, 1921-1939, mainly under the guidance of Baron Friedrich Von Hugel and including transcripts of his letters, 1921-1924, and other items on spiritual advice, confessions, goals and progress; papers relating to retreats and religious writings, 1924-1932 and undated, including notebooks and texts of addresses; printed material by and concerning Underhill, 1926-1941, 1990, including some of her publications; press cuttings, 1891-1949, mainly reviews of Underhill's work but also including early published pieces; sketchbooks and drawings, 1892-1911 and undated, including sketches and watercolours of marine scenes in Britain, ecclesiastical subjects, and Italian and French architecture; photographs, c1925-c1930s and undated, including a photograph and negatives of Underhill (one at Pleshey), a portrait of Baron Von Hugel, marine views, and views of French and Italian castles and towns; material relating to the Underhill family, 1874-1940, including the marriage certificate of Evelyn Underhill's parents, 1874, a family tree, c1891, a copy of Evelyn Underhill's will, 1940, and details of books in Dr Williams's Library, London, which originated from Underhill's library; obituaries of and articles about Underhill, 1941-1997, including theses, bibliographies, memoirs, biographical material and reflections on her work; newsletters of the Evelyn Underhill Association, 1992-1997.

Papers of Alexander Van Millingen on history, architecture and archaeology, c1870s-c1900s (mostly undated), relating mainly to Constantinople and Byzantium but also to Biblical history, Greek and Roman history, history of philosophy and religion, early church history, and history of art, and including manuscript notes (some in notebooks), manuscript and typescript drafts, news cuttings, sketches, transcriptions and rubbings of inscriptions, and a few items of personal material, notably financial accounts and address books; photographs (some labelled as unpublished), plate proofs and sketches of buildings and monuments, and reproductions of inscriptions, including the walls of Constantinople and churches including Saint Eirene, Theodore, Theodosia, Sergios and Bacchos, Peter and Mark, Andrew in Krisis, Ioannes in Troullos, Christos in Chora, and Pantokrator (some items are endorsed with notes); photograph album of people and places in France, Germany, Italy, Austria, England, Montenegro, India, Tunis and Malta, 1889-1895 (where dated); plans of buildings, comprising the Egyptian obelisk in the Hippodrome, Constantinople, and the churches Saint Mary Mouchliotissa, Thekla, Mary Panachrantos, Peter and Mark, Mary Diaconissa, Theodosia, Saviour Pantepoptes, Theodore Thetiro, Mary Pammakaristos, John the Baptist of the Studion, the Church of the Myrelaion, the Monastir Mesjedi, the Refectory of the Monastery of Manuel, the Bogdan Serai, the Sanjakdar Mesjedi, and the Balaban Aga Mesjedi.