In 1868 (through 1878), Davidson was elected reeve of Fullarton Township. In 1875 he was elected the Perth County warden, in a close race with James Trow see (Trow Avenue) of North Easthope Township. Davidson remained the county warden through 1878. From 1878 through 1920 he was the county clerk. In 1900 he was also the county treasurer.
In 1879 he moved to Stratford. After Stratford became a city in 1885, Davidson was elected an alderman, 1887 through 1894. In 1895 he won the mayor's chair, 933 votes to 533. He was also the mayor in 1896. He was returned to the council for three more years: 1899, 1900 and 1902. (see Hibernia Street) for a photo of Mayor James Stamp and the city's 1902 council.
In March 1920, William Davidson climbed a ladder to remove some ice from his house at 135 Church St. The ladder slipped and he fell to the ground. Three days later, on March 8, he died while sitting at a table eating a meal. He was 86. Source: History of Perth, Stratford-Perth Archives