William was born in Norwich in 1890. He enlisted in the army on 4th September 1914 and was posted to join the newly-raised 7th (Service) Battalion Suffolk Regiment. After training, first at Shorncliffe and then Aldershot, the battalion was posted to France on 30th June 1915 and first saw action at Ploegsteert in Belgium. In October that year, William fought in the Battle of Loos and, through 1916, at the Battles of Albert, Pozieres Ridge and Transloy Ridge during the Battle of the Somme.
In 1917, William and the 7th Suffolks were on the front line near Arras and, through April, were involved in the first phases of the Battle of Arras. It was during the latter part of the Battle of Arleux that the battalion sustained large numbers of casualties so, at the beginning of May, they were formed into two weak companies and sent into the reserve to regroup. William Pearson was killed during this last battle. He is buried in Feuchy British Cemetery in France and commemorated on Haughley War Memorial Suffolk.
For his war service, William’s family received the 1914-15 Star and the British War and Victory Medals. He is included in the Melton Roll of Honour published in Booth's Almanac of 1915 and 1916.