The Sinkov mission of January 1941 from America visited the British Government Code and Cypher School headquarters at Bletchley Park, England.
They met British "codebreakers", including Alan Turing, and negotiated an agreement to collaborate on cryptological work (see Ultra).
[2][3] The Holden Agreement of October 1942 gave the United States overall responsibility for Japanese naval codes, although with continued British participation.
[4] The agreement specifically stated that Eric Nave was not to work at FRUMEL the Australian naval codebreaking establishment run by USN Lieutenant Rudolph (Rudy) Fabian.
The American trio worked with Commander Edward Travis (RN), the head of the British communications intelligence (COMINT) facility; and shared their solution to the Japanese Purple machine.