In 1924 the family's banking company, Robert Benson &amp; Co, was reorganised so that Benson became a partner; the firm were largely exposed to US securities, which proved disastrous after the Wall Street Crash, their offices sitting empty for some time. However, by 1934 the firm had recovered most of its lost capital; Benson managed the English and New York trust well enough to see its value nearly double between 1928 and 1935, despite plummeting immediately after the crash. He made business trips to North America, taking out a range of US investments, and in 1936 succeeded his elder brother as chairman of the company. His career was interrupted by the Second World War, when he served as liaison officer to the French First Army until the evacuation from Dunkirk, and then as chairman of the Inter-Allied Timber Commission in 1940, and then from 1941 as Military Attaché at the British Embassy in Washington. After the war, he resumed his chairmanship of Benson's, overseeing the merger with the Lonsdale Investment Trust to form Robert Benson Lonsdale &amp; Co. He was knighted in 1958 for his service as Honorary Treasurer to the English-Speaking Union. The following March, he retired from the RBL's chairmanship, but continued to sit on the board until 1961.