In 2009, the Sri Lankan government won the decades-long struggle against the separatist Tamil Tigers, who had fought a particularly brutal war against the government with regular use of random acts of terror. The Sri Lankan army’s final campaign was marred by excesses, as the soldiers were desperate not to allow the terrorists to escape, even as they used tens of thousands of villagers as human shields to avoid the army’s assault.

There is little doubt that the army was too willing to kill in its determination to stamp out the Tigers, but ever since 2009 the increasingly dictatorial President Mahinda Rajapaksa has totally rejected any accusations of rape, executions and indiscriminate shelling, saying the end of the war had brought peace, stability and the chance of greater prosperity to the country. His total denials are increasingly unbelievable, and Rajapaksa would be better off admitting that excesses were committed and expose them honestly.

This is why UK Prime Minister David Cameron was right in visiting the Tamils in the north of Sri Lanka, and to insist that Rajapaksa accept by next March some kind of international investigation into the army’s conduct. Others have boycotted the Commonwealth summit, like Indian Prime Minister Manmohan Singh. These actions all add to the pressure on the increasingly autocratic government in Colombo to work to essential international standards.