 Tree edited "Forum Magazine" in New York from 1922, and in 1926 became involved in investment on the New York Stock Exchange, before the Wall Street Crash of 1929.Tree returned to England with his wife, the former Nancy Keene Perkins (the widow of his cousin Henry Marshall Field) in 1927, where they had two sons, artist, Michael Lambert Tree and racehorse trainer, Jeremy Tree, and a daughter, who died at birth.At first the couple took a 10-year repairing lease on Kelmarsh Hall near Market Harborough, Northamptonshire which Nancy redecorated with help from Mrs Guy Bethell of Elden Ltd.