Thomas Halliday immigrated to Prince Edward Island from Scotland in 1806 accompanied by his wife, children, and Mary Cochrane (1799-1859), believed to be the only daughter of Thomas Douglas (1771-1820), the Earl of Selkirk. A farm was granted to him in the Belfast area, Prince Edward Island, which was then part of the large Selkirk Estate. He was also a skilled stone mason. He and his wife had six children. Mary Cochrane later married one of Thomas Halliday's sons.

Thomas Douglas, the Fifth Earl of Selkirk, was born on the 20 June 1771, on St. Mary's Isle near Kirkudbright, Scotland, seventh son of Dunbar Hamiliton Douglas and Helen Hamilton. With the death of his father in 1799, Thomas became the Fifth Earl of Selkirk. He married Jean Wedderburn in Inveresk, Scotland, on the 24 November 1807, and they had three children. Shocked by the effect of the highland clearances in Scotland, Douglas proposed to the British government the emigration of Highlanders to Prince Edward Island. The first ship of settlers set out in July of 1803 and arrived on PEI the following month, settling on land in Lots 57, 58, 60, and 62. Thomas Douglas died in Pau, France, on the 8 April 1820.