Lang arrived in Hong Kong in 1904 to join the Gibb, Livingston & Co.[1] He became a partner of the company and also the Mackinnon, Mackenzie & Co.[2] From 1916 to 1927, he was the head of the Gibb, Livingston & Co.[1] He served on the committee of the Hong Kong General Chamber of Commerce and became chairman in 1922 and vice-chairman in 1927.

[1] On 24 November 1921, Lang was elected by the Chamber to represent the business interest in the Legislative Council of Hong Kong during Sir Henry Pollock's absence.

[5] He left Hong Kong in April 1927 for London and his farewell gathering was attended by Governor Cecil Clementi.

Their daughter, Shelia Macnaughton Lang, was born in Hong Kong in 1913.

Their son, William Macnaughton Lang, was born in Hong Kong in 1918 and also worked for P & O in London for many years.