Resident manager at ships agent Karsten Larssen & Co (H.K) Limited
Acting Norwegian Consol during the Japanese occupation 1941-1945. Larssen also acted as Danish Consul in Hong Kong.
Chairman of the Norwegian War Time Committee. After the war Larssen gave a detailed account of the financial transactions and the use of financial aid to the Norwegian authorities and various ships agents.
Larssen was excluded from the list of Norwegians sent to Stanley Civilian Internment Camp in February 1943. Toghether with pastor Johan Nielsen and Haakon Sareussen, among others, Larssen helped to provide financial aid, news and packages to the internees.
He was awared with King Haakon VII's Freedom Cross in 1946 for his effort during the war time.