William ("Will") Edward Arnold-Forster was born into a distinguished military and political family in 1886 as the youngest son of Hugh Oakeley Arnold-Forster, a Liberal Unionist MP and his wife, Mary Story-Maskeline, daughter of Nevil Story Maskelyne. He had three older brothers, Mervyn (Merv), John and Christopher (Kit). He inherited an interest in art from his mother, studying at the Slade School (1905–1908). There, he won several prizes. He moved to Italy in 1911, living near Fiesole in Tuscany until 1914 when he returned to England at the beginning of World War I, joining the Royal Navy and working in the Admiralty, having previously been a naval cadet. Thus, he followed in his father's footsteps[a] and it was at the Admiralty that he met his future wife.
After the war, he married Katharine ("Ka") Laird Cox, who was then working at the Admiralty and moved with her to Zennor on the Cornish coast, near St Ives, where they purchased The Eagle’s Nest.[b] Arnold-Forster was an enthusiastic gardener, and the garden that he created at The Eagle’s Nest was described as spectacular. He also worked on the Memorial Garden at St Ives, and with the sculptor Barbara Hepworth on her garden there. During World War II, Will served in the Home Guard. He died in 1951 at the age of 65.