Davidson grew up in Holywood, Northern Ireland, and was awarded a Bachelor of Arts (Honours) in Law at Trinity College, Cambridge before joining the Foreign and Commonwealth Office in 1985.

[1] Although initially posted as a desk officer for Czechoslovakia and Bulgaria in the Eastern European Department, Davidson undertook Mandarin Chinese language training at the School of Oriental and African Studies before his appointment as Second Secretary for Political/Information at the British Embassy in Beijing from 1988 to 1992.

[2] From 1992 to 1993 Davidson worked as an analyst on terrorism and international security for the Cabinet Office before being appointed as the Head of the China Section in the Far Eastern and Pacific Department of the FCO until 1996.

From March 2005 to September 2006, Davidson was seconded to the private sector as Deputy Chief Executive of International Financial Services London.

[3][4] In September 2014, Davidson married his American boyfriend Scott Chang (Chinese: 張志鵠) in a ceremony officiated by British Ambassador Sir Sebastian Wood at the Ambassador's residence in Beijing, causing a stir in China, [5] where same-sex marriage is not permitted.