Eleanor Brett, Viscountess Esher kept a typescript entry for most days during the First World War, ranging in length from a single line to a paragraph, sometimes reproducing extracts from letters, telegrams, and newspaper articles. She appears to have written her diary retrospectively. Throughout her diary, she interspersed short anecdotes from soldiers about their military experiences and character profiles of politicians, diplomats, journalists, nurses, artists, and other individuals she meets through her and her husband, Reginald’s work.

Subjects for 1914 include records of her and Reginald's work and travel arrangements as they split their time between London, Paris, Boulogne [France], and Scotland. In August 1914, Eleanor recounts how she was asked by Sir Perrott [Sir Herbert Charles Perrott, Chief Secretary of St John’s Ambulance Associations], to run ambulance classes. She had begun running classes in 1909, which she describes as leading the War Office to create Voluntary Aid Detachments (VAD). In September 1914, Eleanor began co-ordinating the Territorial Relief Fund, supported by money from Sir Joseph Duveen. The fund was initially aimed at supporting poor women, but soon extended to aid men with disabilities caused by war to return to civilian life. Eleanor also records visits to various military hospitals, such as the British Red Cross Headquarters in Champs Elysees Paris, [France], commenting on their overall conditions and individual personnel. She often comments on the people she encounters on her crossings over the Channel.

Subjects for 1915 include observations, events, and meetings in France, England, and Scotland. She describes her near-death experience swallowing a chicken bone, her first experience of an air raid in Paris, reflections on buying a new uniform, as well as visits to hospitals such as the Scottish Women’s Hospital at Royaumont [France] and visiting exhibitions of artwork created by injured soldiers based in France. She also records meetings held between Reginald and various government and military officials, with occasional extracts from Reginald on the changing military situation.

Subjects in 1916 include receiving the Red Cross Award at Buckingham Palace; observations from various visits to French camps and hospitals, including as part of the Red Cross Inspector Tour; arranging the provision of prosthetic limbs for injured soldiers; writing an article for the Westminster Gazette on the Women’s Emergency Canteen; visiting exhibitions of soldiers’ artwork; learning about new medical treatments, and meeting various members of the Royal Family, including Prince Louis of Battenberg and Prince Arthur of Connaught.

Subjects in 1917 include accounts on the formation of the Hackett-Lowther Ambulance unit in France; excerpts of Reginald’s writing on Lord Kitchener and Lord Binning; visits to the German lines; a transcription of a letter sent to the Territorial Force Association Meeting reflecting on her work; supporting French villagers in rebuilding their communities; a holiday in Biarritz [France]; observations on living in Paris.

Subjects in 1918 include moving back to London from France; her experience of air raids in London; visiting Scotland for the first time in nearly two years; the death of the Tsar; and voting for the first time. She notes how she stopped keeping a daily diary from March to April owing to the monotony of her life.