Gimson entered the
British Ceylon Civil Service as a
cadet in November 1914. In the beginning he was attached to the Office of the Naval Intelligence Officer in addition to his own duties. Later on he became an additional
police magistrate in
Colombo. In 1918 he was sent on military service during the
First World War and returned to the colonial administration as an additional assistant
colonial chief secretary in July 1919. Two months later he was transferred to
North Central Province as
assistant government agent. Gimson was appointed
additional assistant colonial secretary for the second time in March 1920 and was promoted to the post of 4th assistant colonial secretary in September 1920. Subsequently, he was sent to
Mannar as acting assistant government agent in February 1922. In February 1924, he was promoted to the Customs Department as landing surveyor and acted as acting deputy controller from March to May in 1928. Gimson left the Customs in March 1929 and was appointed as an additional assistant to the Director of Education. Later in July 1931 he became secretary to the Minister of Education. In February 1932, Gimson was appointed assistant government agent of
Trincomalee and in December 1933, appointed assistant government agent of
Kegalle. In August 1935, he was involved in a special duty to help organise the forthcoming general election of members of the
state council. Afterwards, he was appointed the chairman of the
Municipal Council of
Kandy in June 1936 but was eventually given the post of Controller of Labour in 1937. Gimson held this office until 1941 and he gained the rank of class one officer in 1938.
Colonial secretary of Hong Kong Gimson was promoted to the post of
Colonial Secretary of Hong Kong in 1941 and arrived at the colony on 7 December, just the day before the
Japanese Army initiated its unexpected and sudden large-scale invasion to Hong Kong. The defence forces of Hong Kong soon lost in the
Battle of Hong Kong and the then
governor,
Sir Mark Young, was forced to surrender on 25 December, which is now known as the
Black Christmas. After the Japanese victory, all British officials were arrested and were under Japanese rule. Since the Governor was interned elsewhere, Gimson became the representative of the former government who was responsible for dealing with the Japanese over the issue of transfer of power. For some time he even set up a provisional liaison office in
Prince's Building,
Central. In March 1942, Gimson was finally sent to
Stanley Internment Camp, where most British colonial officials and expatriates were interned. During the internment, the British civilian internees established the "British Communal Council", which tried in a limited way to maintain the life and order in the camp. As the highest-ranking British official in the camp, Gimson became the chairman of the council and was also responsible to negotiate with the Japanese on matters relating to the camp. After three years and eight months of
Japanese occupation, the Emperor of Japan finally announced an
unconditional surrender to the
Allies on 15 August 1945. Immediately after the unconditional surrender was made, the Japanese authority had to continue to maintain the order of Hong Kong as the Allies were still on the way to take over. However, all the prohibitions and regulations set by the Japanese were entirely lifted and abolished instantly. On the other hand, on the eve of the surrender of Japan, the
British Ambassador to China,
Sir Horace Seymour, had already tried to make contact with Gimson from
Chongqing, urging him to exercise the sovereignty on behalf of the British government. Although Seymour's order arrived late on 23 August, Gimson had declared himself "acting governor" and had started to prepare for a "provisional government" on 16 August after knowing Japanese had surrendered. Receiving Seymour's order on 23 August, Gimson and other internees left the camp and took over the authority from Japan. Gimson was sworn as acting governor by Chief Justice
Atholl MacGregor. He and other former colonial officials set up the headquarters of the provisional government in the
Former French Mission Building. On 27 August, Gimson made a further announcement through radio, stating the provisional government had been established. Nevertheless, at the beginning of the provisional rule, the government had to rely on the Japanese troops to maintain the order of Hong Kong since the power of the administration was limited. On 30 August 1945,
Rear Admiral Cecil Harcourt and his warships entered
Victoria Harbour. Since Harcourt was asked to form a
military government by London, Gimson transferred the power to him and the military government was officially formed on 1 September. Harcourt himself became the head of the military government and Gimson was appointed
lieutenant governor by him. Yet, the creation of the office of lieutenant governor was deemed unsuitable by the
Colonial Office and therefore Gimson was soon replaced by a chief civil affairs officer and his team sent from London on 7 September. Gimson himself was in fact in poor health as a result of more than three years of internment. For health reasons, he left for the United Kingdom on 16 September. On the day before his departure, he commented in a radio programme that Hong Kong should undergo political reform in the future.
Governor of Singapore After spending some time recovering in the United Kingdom, Gimson became
governor and commander-in-chief of Singapore when the
Straits Settlements colony came to an end on 1 April 1946. He abolished the military government which had been set up by
Lord Louis Mountbatten (as he then was) in 1945, and reinstalled a colonial civil administration. As Singapore was now a separate
Crown colony, both legislative and executive councils of Singapore were established. In the first two years of Gimson’s governorship, the recovery of the economy in Singapore was slow, and in 1947 a large riot broke out. In March 1948, Gimson allowed six of the twenty-five seats in the legislative council to be elected. the Colonial Police Medal in 1948. In June 1948, an
armed insurgency by communist groups in
Malaya broke out, and the British imposed harsh measures to control left-wing groups in both Singapore and Malaya; the controversial
Internal Security Act, which allowed indefinite detention without trial for persons suspected of being "threats to security", was enacted in Singapore at this time. Since the left-wing groups were the strongest critics of the colonial system, progress on self-government stalled for several years. The colonial government also tried to prevent contact between Singaporean Chinese and the
People's Republic of China, which was
proclaimed by
Mao Zedong in October 1949.
Tan Kah Kee, a Singapore businessman and philanthropist, made a trip to China in 1949 and was denied re-entry into Singapore when he planned to return in 1950. In April 1950, Gimson was the target of an unsuccessful assassination attempt in Singapore: as he left a boxing event at which he had been presenting prizes, a grenade was thrown at him which bounced off his leg and exploded harmlessly some distance away. A second legislative council election was held in 1951 with the number of elected seats increased to nine, but the colonial administration was still dominant. Gimson retired from the colonial service the following year and left Singapore on the P&O Liner
Corfu on 20 March 1952. He was succeeded in the post of governor by
John Nicoll, another former
Colonial Secretary of Hong Kong. == Personal life ==