The British Western Pacific Territories did not have an own flag. The separate components had one, if it was a colony de jure, because since 1865 ships of colonial governments were permitted to fly the Blue Ensign with a badge in the flying end of the flag.
Under the name "British Western Pacific Territories" (established in 1877) had summarized all British possessions in the (western) Pacific, which did not had been a self-administrated colony. Those possessions indeed had been British possessions, but je jure no colonies, and had not been subordinated under a governor. The High Commissioner for the Western Pacific was responsible for those islands. Until 1952 that function was bond on the function of the governor of Fiji. It was abolished in the year 1976. Between 1877 and 1976 belonged some archipelagos for different times to the British Western Pacific Territories:
