 According to the 1906 "Jewish Encyclopedia", Gideon began business in 1720 with a capital of £1,500 (worth £176,100 in 2019) inherited from his family, which increased so rapidly that in 1729 he was admitted a sworn broker with a capital of £25,000 (worth £3,670,000 in 2019).Gideon was involved in financial activities as a broker, a middle-man in the metal trade with the British East India Company.He was one of a number of contemporary Sephardic financiers in British public life who specialised in metal brokering, along with Abraham Mocatta.