Harold Henry Hill Simpson was born on 17 March 1897 at Bay View, Prince Edward Island, the son of Donald Montgomery Simpson and Ellen (Nellie) Montgomery Ramsay. Following studies at Prince of Wales College in Charlottetown, he considered entering the mission field but in 1915 he enlisted with the Canadian Expeditiary Forces. He served throughout World War I in England, France, Belgium, and Germany with the Second Canadian Siege Battery, seeing action in many major battles including the Somme, Vimy, Passchendaele and Ypres. In 1966 he published "A history of the Second Canadian Siege Battery, June 1915 - May 1919, with recollections by Allan Cole (92715)".

Harold married twice, first to Hazel White in 1920, and second to Alice Hazel Rayner in 1928. He and his second wife had three children: Anita Mae Jean, Douglas Reagh, and Donald Owen. For many years he worked for the Atlantic Division of the National School and Libraries Services of Grolier Canada. In his seventies Harold became intensely interested in his family genealogy and in the history of Cavendish, the community founded by his ancestors. He set about to collect information on this subject and on the other founding families of Cavendish and, in 1973, published "Cavendish, its history its people". He was also the prime organizer of the Cavendish Bi-centennial celebration in 1975. Harold died a few months later in the same year in Amherst, Nova Scotia.