In one classroom of white-washed walls and wooden desks a group of seven-year-olds learn to pipe on the bamboo Chinese flute. Of 40 students just nine are girls.

Next door, another class practice their calligraphy, copying down hieroglyphs in neat rows. Once again, most of the children grappling with their pencils are boys.

The little girls of Wuxue are not being denied an education. Rather, they simply don’t exist. According to official statistics, for every 100 girls there are 197 boys.

It is the worst example of gender imbalance in China, but a similar pattern exists across the country. The cause is an unintended result of the one-child policy: sex selective abortions.