William Tanner was already a prosperous landowner in England, owning two estates when he arrived in Western Australia in 1831 with his wife Hester and son. He had successfully invested the capital he had received upon the death of his father which helped fund his ventures upon arrival into the Swan River Colony. A very talented businessman with a vast knowledge of farming, he was able to adapt these techniques to suit the climate and conditions in the Colony.

In addition to his original 1831 land grant which he named Baskerville, in 1832 Tanner was granted Lieutenant Preston’s property adjacent to Success Spring 31 Swan location P (1281 acres) dubbing it Lockeridge and the West Guildford villa lot Q2. In 1834, his neighbour The Rev. J. Wittenoom sold his 20 acre lot designated R1 to Tanner. In 1837, Tanner further extended his West Guildford holdings by having his agent (Tanner was at that time in England) purchase the 1531 acres of lot Q1, the former Government reserve, which had originally comprised both lots Q1 and Broun’s estate. Thus, by the late 1830s, William Tanner had established himself as the largest single owner of land in what was later to be the town of Bassendean, holding overall approximately 50 percent of the district.

In 1833 Tanner leased Woodbridge from Captain Stirling and contemplated building a home at Lockeridge but this did not eventuate. He also leased Caversham Estate in the late 1830s and early 1840s, but his primary residence remained at Baskerville until 1843 when he listed his address as Wexcombe, another of his Swan landholdings.

In 1841 he leased land to Edward Hamersley for £1,200 only to lease it back again two years later, and in 1851 the Villa lot was sold by his agents to Charles Pratt. The remaining West Guildford estates were kept intact until 1897 when they were sold by the executors of his estate.

In addition to his considerable land ownings and interest in farming and agriculture, Tanner was very involved in civic affairs and the social and political life of the colony. He became spokesperson for the anti-government faction voicing his and other landowners concerns in relation to who could hold land. Tanner believed military personal were favoured over other settlers who were excluded from decision making. He organised several public meetings and was appointed as a member of the Legislative Council in 1840. He was also appointed as a magistrate for the upper Swan district, a position with great responsibility especially in relation to the inescapable and unresolvable conflict of interests between the Aboriginal inhabitants and the white settlers. Tanner was fully aware of the prior claims of the Aboriginals, but he was determined that they should not hamper the economic aims of the white investors.

In another venture, Tanner partnered with Francis Lochee and found the Inquirer newspaper in competition with the establishment and government-biased Perth Gazette. The Inquirer was an immediate success and soon had double the circulation of its opponent.

Tanner furthered expanded on his ventures, developing an interest in colonial banking. He was a director and one of the major shareholders in the reconstituted Western Australian Bank and was elected as chairman of the Agricultural Society in 1841.

Tanner made several trips back to England, in large part due to his wife’s homesickness. It was on one of these trips that William died in 1844 and in his will, he appointed his brother-in-law Oriel Viveash and his friend William Brockman as trustees for the estates which he stipulated were to be kept for his children until they came of age.