Born in Cawnpore, India, Clementi was the son of Colonel Montagu Clementi, Judge Advocate General in India, and his wife, Isabel Collard. He attended St Paul's School and Magdalen College, Oxford, where he studied Sanskrit and the classics. In 1896, he achieved a first-class result in mods, and was awarded a Boden Scholarship in Sanskrit in 1897. He was given honorable mentions for the Hertford, Ireland and Craven scholarships. Clementi was proxime accessit for the Gaisford Greek Prose prize in 1897, and obtained his B.A. in 1898. Clementi was also proxime accessit for the Chancellor's Latin Essay prize in 1899, and obtained his M.A. in 1901.
Early colonial service
In 1899, Clementi placed fourth in the competitive examinations for the civil service, which allowed him his choice of postings. His choice was Hong Kong, and upon his arrival he was sent up to Canton, where he was a land officer until forced to return to Hong Kong by the events of the Boxer Rebellion. Clementi's facility with languages was demonstrated when he passed the Cantonese examination in 1900, and the Pekingese examination six years later, in 1906. After serving as an Assistant Registrar General in 1901, Clementi joined as a member of the Board of Examiners in Chinese, in 1902. In 1902, Clementi was seconded for special service under government of India and was created J.P. in that same year. A year later, he was seconded for famine relief work in Kwangsi. A year afterwards, Clementi was appointed Member of Land Court, Assistant Land Officer and Police Magistrate at New Territories, Hong Kong, a position he served in until 1906. Due to his outstanding performance in the services, Clementi was promoted to Assistant Colonial Secretary and Clerk of Council, in 1907. While he was in that position, Clementi represented the Hong Kong government in the International Opium Conference at Shanghai, in 1909. A year later, he became the Private Secretary to the Administrator at that time, Sir Francis Henry May. Clementi eventually became Acting Colonial Secretary and Member of both the Executive and Legislative Councils of Hong Kong. He would remain there until 1912. Clementi played a part in the founding of the University of Hong Kong. Indeed, he wrote the words, in Latin, of the University Anthem, first performed 11 March 1912. In 1913, Clementi was appointed Colonial Secretary of British Guiana, a post he held until 1922. From there he was named the Colonial Secretary of Ceylon, where he served until 1925. Each position imparted considerable responsibility, and on more than one occasion he was in charge of administering the entire government of his area of responsibility. Whilst in Ceylon he served as President of the Ceylon Branch of the Royal Asiatic Society in 1924.
Governor of Hong Kong
In 1925, Clementi was appointed as Governor of Hong Kong, a position to which his fluency in Cantonese suited him well and in which he served until 1930.
During his tenure, the Canton–Hong Kong strike, which crippled the Hong Kong economy, was resolved and Kai Tak Airport entered operation. He also notably ended the practice of Mui Tsai, the traditional Chinese "female maid servitude" system which often resulted in the abuse of young servant girls. He also appointed Shouson Chow, a prominent Chinese merchant, as the first unofficial member of the Executive Council. At the same time, he increased the numbers of official and non-official members in the Legislative Council from eight to ten and from six to eight, respectively. He invited one Chinese and one Portuguese to be Unofficials.
Governorship of the Straits Settlements
After his tenure as Governor of Hong Kong ended, Clementi went on to serve his last post in the Colonial Services as Governor and Commander-in-Chief of the Straits Settlements, which included Singapore, and High Commissioner for the Malay States, from 5 February 1930 to 17 February 1934. He handed over to Sir Andrew Caldecott, who become acting Governor, and left for England due to his illness. The position of Governor was later filled by Sir Shenton Thomas on 9 November 1934. Six years later, in 1940, Clementi became the Master of the Mercers' Company.
