Vengalil Krishanan Krishna Menon established a reputation as one of the most controversial and divisive figures in Indian and broader Cold War politics. Under Nehru’s patronage, Menon experienced a meteoric rise to political power. In 1947, he was appointed to the prestigious post of Indian High Commissioner to the United Kingdom. However, his abrasive personality and readiness to listen to and, on occasions, publicly endorse, Soviet and Communist Chinese positions on a range of international questions ruffled feathers in London and Washington. In the United States, officials characterised the Indian diplomat as ‘venomous,’ ‘violently anti-American,’ and ‘an unpleasant mischief-maker’. Many British diplomats echoed such sentiments. This chapter examines the British government’s response to Krishna Menon’s appointment. It explores the nature of Menon’s relationship with the CPGB, the risk that communists working for him posed to British security, and the strategy that MI5 developed to meet it. It illustrates the Attlee government’s conviction that India, and more particularly, Krishna Menon, represented a weak link in the Commonwealth security and intelligence chain.