Soviet government that the Chairman of the Trade Delegation, Mr. Khinchuk, was protected by diplomatic immunity in accord with the Anglo-Soviet Trade Agreement of 16 March 1921. In an attempt to provide justification for the raid on Arcos, Prime Minister Stanley Baldwin read aloud in the House of Commons from a handful of deciphered telegrams, specifically one mentioning Comintern agent Mikhail Borodin, that proved Soviet guilt of espionage. Baldwin admitted that these telegrams were not acquired in the Arcos raid, but stated they were evidence that the Soviet Union was using the organisation for the conduct of "military espionage and subversive activities throughout the British Empire and North and South America". As a result of this the Soviets, now aware that the British secret services had been intercepting their communications, changed their encryption cyphers for all diplomatic communication. They adopted the virtually unbreakable one-time-pad system, therefore eliminating the ability of the British GC&CS to decipher any high grade Soviet messages from 1927 until the end of the Second World War. Britain severed diplomatic and economic ties with Soviet Union shortly after the incident in late May 1927, marking the end of the Anglo-Soviet Trade Agreement, and a war scare swept the Soviet Union. Despite the highly publicised raid of Arcos and the manpower and time put into the operation, little of practical import resulted from the raid. Historian Louis Fischer noted of the Arcos raid: During its six years of existence, Arcos did approximately £100,000,000 in trade between Britain and the Soviet Union. See also Campbell Case Zinoviev letter 1926 General Strike Nanking incident of 1927 Woolwich spy ring Amtorg Trading Corporation aka AMTORG (NYC) Russian Soviet Government Bureau aka Soviet Bureau (NYC) Footnotes External links Economic history of the Soviet Union Russia–United Kingdom relations Foreign relations of the Soviet Union Companies of the Soviet Union Soviet Union–United Kingdom relations 1920 establishments in the United Kingdom Organizations established in 1920 Foreign trade of the Soviet Union