He travelled extensively over China both before and during Second Sino-Japanese War, being in Canton at the time of the fall of the city to the Japanese.
In 1966, Baker was appointed Bishop of the Anglican Diocese of Hong Kong and Macau, succeeding Ronald Hall.
He was chosen following the decision of the previous bishop-elect, Joost de Blank (former Archbishop of Cape Town), not to take up his new appointment due to ill health.
In February 1971, the Anglican Consultative Council (ACC) held its first meeting in Limuru, Kenya, each province sending a bishop, a priest, a layman and a woman observer.
On 28 November 1971, Baker ordained Jane Hwang and an English CMS missionary, Joyce M. Bennett, to the priesthood.