This series includes Nicholson's unpublished autobiography on which he had been working for many years. The work is rich in anecdotes, discussion of his beliefs and philosophies with regard to the environment and human institutions, analysis of his own character, and details covering the key activities of his life, including his childhood and youth. There are other autobiographical drafts and notes in this section and material relating to various interviews that he gave between 1970 and the last years of his life, including his appearance on BBC Radio 4's 'Desert Island Discs' in 1995.

Childhood material, dating from 1913, chiefly consists of bird lists and diaries (some from trips to France and Germany); in addition there are other natural history notes and some school exercises and reports. Papers covering Nicholson's years at Hertford College, Oxford, are slight: significant material relates to his involvement in the Vane Society (play-reading).

There is an exceptionally good collection of Nicholson's hand-written journals covering, intermittently, the period from 1964-1994, with a few pages of entries from the 1940s. Some of these document UK and overseas travel, while a numbered series of ten journals cover most of his activities during 1970, including records of conferences and discussions, thoughts and observations, and family matters. Engagement diaries date from 1995 to 2001. There is some documentation of holiday travel, particularly during the 1980s and 1990s, with notes or detailed accounts of trips often included.

A small quantity of family correspondence dating from 1929 survives; other personal correspondence spans the period 1927-2002. There is also material concerning personal engagements and some miscellaneous papers which include various official documents.