If you wander down a rutted dirt road on the edge of Phnom Penh, past grilled banana stands and children peddling bicycles, you might hear the strains of an Italian aria drifting across a high fence.

It's 8pm and a full moon illuminates the Sisophon night sky. Two clowns wearing black make-up, billowing trousers, and felt wigs stumble out on to the stage behind a plump lady adorned in an emerald ...