Born in Hong Kong on 16 January 1879, Arnhold was a British Jew of German ancestry.

[3] The family moved to London and were naturalised in 1882; in 1891, at the age of 12, he and his brother Charles were baptised at St Mark, Notting Hill; and he was educated in Britain.

[5] Arnhold's third marriage in the early 1940s was to Esther Jean née Miller (1898–1965) of Oregon, USA previously the wife of William Selman Gassaway (1901–1981).

Sir Victor Sassoon became the majority shareholder in 1923 after a merger[14] According to Stella Dong, its "most attractive asset was the Cathay Land Company, ownership of which gave Sir Victor control of a number of apartment buildings and a hotel in the Shanghai International Settlement as well as choice housing estates in the French Concession.

"[15] Arnhold's served as a front for Sassoon's political interests in the International Settlement.

[18] Arnhold & Co. flourished until 1949 when, with the change of Government in China, the headquarters relocated to Hong Kong.

Mr. Maurice Green who had been associated with the company since the Sassoon takeover, acquired the controlling interest in Arnhold in 1957.

[26] Arnhold decided not to contest re-election to the council in the elections held on 5–6 April 1937.