Andrew Duncan was Sheriff Substitute for Shetland. Sheriff's Closs (now Law Lane) was named after him. In 1806 he was appointed Captain Commandant of the Lerwick Volunteer Infantry, a post he held until their disbandment in 1814. At a meeting of the burgesses of Lerwick on 2 April 1818 he produced the charter, dated 10 February 1818 creating Lerwick a Burgh. In 1819 he built Prospect House on the site of an old fort or battery which commanded the southern approach to Lerwick Harbour. Also in the same year, on the instructions of The Court of Session he complied a population census of the town of Lerwick. He also used these census figures to act as advisor on the required seating capacity of Lerwick Parish Church, thus settling a dispute with the Heritors of Lerwick. Andrew married Grace Scott , daughter of Walter Scott Sheriff Substitute for Shetland 1787 - 1808, direct descendants of the Scott of Scottshall family. Their second child, and eldest son, also named Andrew Duncan , was a lawyer, and represented the plaintiff in the Eunson vs. William Arthur Bruce of Symbister and the Bruce of Symbister Estate in a tenancy dispute involving several years of litigation in the late 1840's and early 1850's. His brother, Gilbert and his son Charles were councillors. Andrew and Grace's fifth child, and third son, William Rae Duncan , was appointed Lerwick Postmaster in 1833 and his grandson, William was a Zetland County Councillor. When he retired, he was succeeded by Robert Bell on 17th November, 1843.