British occupation zone in Germany
In May 1949 the British, French, and American zones were joined to form the Federal Republic of Germany.  The military governors were replaced by civilian high commissioners.  The high commissioners were part-governor and part-ambassador.  The occupation officially continued until 1955.  This is when the Federal Republic became a fully sovereign state, the western occupation zones ceased to exist, and the high commissioners were replaced by normal ambassadors. But the four allied powers still had special rights and responsibilities in Germany until the Final Settlement of 1990.