Australia has been repeatedly criticized for its immigration policy. The UK is counting the cost.
Migration is economic, people seeking a better life.
Despite its apartheid policy, Africans came from the north in droves to work in South Africa. Burmese migrate to Thailand because pay is three times what they get in Myanmar.
Climate change will bring about a new wave of migration. When the flows of water from the Tibetan flow to the Ganges, Brahmaputra and Mekong are halved, 1 billion people will be on the move.