Between 1907 and 1935, he held various appointments in the Malayan Civil Service, including:

• Acting Controller of Labour
• Under-Secretary to the Straits Settlements
• Commissioner of Lands Federated Malay States
• Secretary for Postal Affairs
• Acting British Resident at Negri Sembilan
• Acting British Resident at Perak
• and British Resident at Selangor.

Later in his time in Malaya, Caldecott served as:

• Chief Secretary to the Government of the Federated Malay States (1931–1933)
• Colonial Secretary to the Straits Settlements (1933–1935)
• Officer Administering the Government of the Straits Settlements and High Commissioner for the Malay States (1934).

Through his experience in the Malayan administration, Caldecott was famous for his ability to settle quarrels between different ethnic groups.