Arthur John Alexander Jardine was a British officer who began his career in the Indian Police in 1879. He was experienced in policing and later transferred to serve in the Burma Police. In 1897, when the Siamese government sought to modernise its police force, they requested a police officer from the British government in India.

Jardine was chosen and travelled to Siam to become Director of the Bangkok Police, which was then called Kongtrawen. He used his expertise to improve both the administration and the personnel of the force, introducing a well-organised Western‑style hierarchy. He combined the separate divisions — including the outer-city police, inner-city police, and railway police — into a single, unified force. He also established a clear chain of commands, with ranks such as Director, Deputy Director, District Commanders, Sub‑district Officers, and Senior Inspectors.

To enhance capability, he proposed hiring 200 Indian policemen to train Siamese officers in weapon handling and riot control. He also recommended establishing a police school to systematically train new recruits. Jardine modernised the police uniform by replacing the traditional blue with khaki, paired with black leggings and a black helmet with a red crest. This cooler and more practical uniform earned the nickname “red head, black legs”.

He also drafted regulations for conducting inquests, improving the process of evidence gathering by involving police officers, district officials, villagers, and physicians. Jardine further recommended rebuilding police stations with solid materials to replace temporary bamboo structures and advocated for fair salaries and promotions to improve morale. Although he served only five years in Siam, his reforms gave the police force a clear structure and standards comparable to modern nations. His work laid the foundations for the development of the Royal Thai Police into a professional and efficient organisation.