At one stage, it was hoped to build a joint design that would meet both the Royal Navy's requirement for a low-cost Patrol Frigate and Australia's General Purpose Escort requirement, with discussions between the two navies beginning in 1967, with Australia, who hoped to build a series of Type 21s in Australian shipyards, part-funding design work on the proposal. The requirements of the two navies were significantly different, with Australia wanting higher speeds ( rather than the requirement of the Royal Navy) and American armament (including Sea Sparrow missiles and a Mark 45 gun), and Australia pulled out of the project in November 1968, later refining its requirements into the Australian light destroyer project. After the Royal Australian Navy (RAN) DDL was cancelled the RAN and Royal New Zealand Navy (RNZN) reconsidered the Type 21 but still found it too expensive, and considered the UK gun and radar inferior to the United States Navy options. Australia ordered the US design in 1976.