Earlier this month, Singapore’s Ministry of Foreign Affairs identified Professor Huang Jing, a prominent academic at the Lee Kuan Yew School of Public Policy (LKYSPP), as “an agent of influ­ence” of an unnamed foreign country. “Huang used his senior position in the LKYSPP to deliberately and co­vert­ly advance the agenda of a foreign coun­try at Singapore’s expense,” the ministry said in a statement.

Political espionage is as old as human history, of course, and the only wrong is being caught.

In the early years of China’s Southern Song dynasty (1127-1279), the prime minister himself might have been an agent of Jin, the Jurchen state in the north.

Qin Hui had been among the Chinese ruling elite and cap­tured by the invading Jin army in 1127. While in captivity, he found favour with the Jin rulers, and in 1130, he suddenly appeared back in the Southern Song capital, in present-day Hangzhou, claiming to have escaped. The fact that his entire family and retinue of ser­vants returned with him did not escape his detractors, who thought his tale spurious.

Qin’s political star rose, however, and, as prime minister, he fought hard for appeasement with Jin to avoid war, in the process executing able military com­manders such as Yue Fei.

While it’s not absolutely certain that he was a spy for the Jurchens, Qin is still public enemy No 1 in China, 862 years after his death.