Acland joined the Unitarian Society in 1803, address Peckham.[5] That year Gideon Acland & Co., grocers and sugar-factors, were in business at 57 Cannon Street, London.[6] In 1805 Acland was a commodity broker. He fell victim to James Elkin Daniels, later a notorious fraudster, in a forward bargain deal over saltpetre. He ended as a creditor, money he had paid on behalf of Daniels being treated as a forced loan.[7]
In 1812 Acland was one of a group of petitioners against the 1807 Orders in Council, restricting trade with continental Europe, asked to give evidence to a parliamentary committee.[8] The Alumni Cantabrigienses entry for his son Charles indicates that he was at some point a merchant at Antwerp.[9] In his testimony, Acland said that the effect of the 1806 Berlin Decree, in which Napoleon restricted trade with the United Kingdom, was via strict enforcement in Dutch ports to tie up much shipping, including vessels under his direction, during 1807, and also at Bremen.[10]
In 1814 Gideon Acland & Co. was advertising sales of indigo and coffee.[11] Acland's Mincing Lane partnership as sugar brokers with James White was dissolved in 1815.[12] The leading case in bankruptcy law Lucas v Dorrien from 1817 related to West India Dock Company warrants for sugar and molasses in warehouses, made out in favour of Gideon Acland & Co. (or G. Ackland & Co.)[13][14]
Their eldest son, Gideon Acland II, was admitted to Gray's Inn in 1820.[16] In a Loyal Declaration of that year to George IV, he associated with the Colonial Mart Warehouse, 9 Mincing Lane and Robert Heale.[17] He married in 1825 Elizabeth Allen, daughter of John Allen of Tiverton and Elizabeth Acland, and sister of Peter Allen who was a founder of the Manchester Guardian. Elizabeth Acland was a sister of his father, making this a first-cousin marriage.[18][19][20][21] The brokers Acland & Barrow of Mincing Lane were active in 1822, selling rhubarb and soap;[22] the partnership of Gideon Acland and John Barrow was dissolved in 1826.[23]
Acland and his wife ran a school in Perth during their time there, and Acland became part of the story of the 1833 fatal duel between John Wilson and Robert Lyon: Elizabeth Hughes who was the central figure in the events leading to the duel was a teacher in the school, and Wilson wrote to Acland with allegations about her behaviour.[28][29] Acland adopted for a time David John Hughes (1820–1915), her brother; he was later adopted by Wilson, who married Elizabeth.[24][30] The school closed, and the Aclands moved from Perth.[29]
Gideon II's only daughter Emily Maria married in 1847 Russell Scott Taylor, eldest son of John Edward Taylor.[31] After his death, she married in 1854 Jules Delbrück of Paris.[32]