The collection includes correspondence; drafts of books, articles, broadcasts, and speeches; family papers; a photocopy of a diary; and photographs.

Some of the highlights of the collection include correspondence and papers relating to William Strang's career in the Foreign Office, including the Metro-Vickers trial in Moscow, 1933, Appeasement policy, 1938-9, and his relations with the Foreign Office during that period; and the work of the European Advisory Commission, 1943-5, and the British Control Commission in Germany, 1945-7. There are numerous letters exchanged between William Strang and historians interested in his memories of people and events during his Foreign Office career, particularly during his time as Joint Permanent Under-Secretary (Germany Section) and Permanent Under-Secretary, and photographs illustrating different stages of his diplomatic career.

The collection includes photocopies of a diary he kept while on active service in France and Belgium, 1916-17. The originals of this diary are in the Liddle Collection at Leeds University Library's Special Collections.