This collection has been divided into 3 sections:

• D674/1 Letters from, to and about Mary Kingsley
• D674/2 Articles by and about Mary Kingsley
• D674/3 Unpublished typescripts

George Augustin Macmillan (1855-1936), publisher, was the second son of Alexander Macmillan who had, with his brother Daniel, founded the publishing company Macmillan in 1843. George Macmillan was educated at Eton, where he held a King's Scholarship. He entered the family firm in 1879 and married Margaret Helen Lucas, daughter of Joseph Lucas, in the same year. It was Macmillan who published Mary Kingsley's Travels in West Africa (1897) and West African Studies (1899), so continuing the literary friendship between the Macmillan and Kingsley families: Alexander had in 1855 published Charles Kingsley's Westward Ho!. George Macmillan eventually became the Director of Macmillan, as well as the Chairman of Stainer & Bell Ltd.

Mary Henrietta Kingsley (1862-1900), English traveller, ethnologist and author, daughter of George Henry Kingsley (1827-1892), brother of Charles Kingsley, was born in Islington, London on 13 October 1862. She studied sociology at Cambridge, and on the death of her parents resolved to study religion and law in West Africa. She sailed to the Gulf of Guinea port of Calabar, on the coast of what is now Nigeria, and from there travelled inland. From the Niger River region to the north, she travelled southward as far as the lower Congo River region in what is now northern Angola. Throughout the trip she studied African religious practices, such as "Fetish". She returned to England in 1894 but travelled again to West Africa later that year, stopping first on the coast of what are now Cameroon and Gabon. In Gabon she travelled by steamboat up the Ogowé River. At Lambarn, she continued her river journey by canoe into the Great Forest region, territory that was then seldom visited by Europeans. After studying the life and culture of the region's Fang people, she returned to the Cameroon coast. Before her return to England in 1895, she climbed Mount Cameroon (13,760 ft), the area's highest peak.

Kingsley wrote three books about her experiences in Africa, Travels in West Africa (1897), West African Studies (1899), and The Story of West Africa (1899), and lectured extensively in Britain after returning from Africa. Her books were very popular and well respected by her contemporaries, but some of her unconventional views on African society and British colonial policies provoked dismay in England. A notorious advocate of the African liquor trade, Kingsley also criticised missionary tactics and was known to have referred to "the missionary-made man" as "the curse of the coast". Kingsley appeared to rejoice in challenging conventions: she once declared in a letter to her friend Margaret Macmillan "it is jam and fritters...to know I have upset somebody" with something she had written. For the Africans who encountered Kingsley and her charitable work, however, she was a "real and true friend".

Kingsley made her final trip to Africa in 1899. She had intended to visit West Africa again, but the outbreak that year of the Boer War led her to travel to South Africa instead. While working in Simonstown as a nurse caring for Boer prisoners of war, she contracted typhoid fever and died, aged 38. Kingsley's death was widely reported by newspapers in Africa and England, and there were proposals in both places to construct memorials in her name. One of these, "The Mary Kingsley Society of West Africa", now exists as "The Royal African Society".