Ching Ching greets Chia Chia, December 1981In September 1974, two adolescent pandas left what was then Peking now Beijing for Britain, a gift from Chairman Mao Zedong to the then prime minister, Edward Heath. Within three weeks of the animals arrival, visitor numbers to London Zoo doubled, to 16,000 a week. But despite high hopes for the pair breeding, they showed no romantic interest in one another. So, in 1981, they were separated for nine months while Chia Chia, the male (right), was