The UK economy would be 3.6% smaller by 2040 if net migration fell to zero, forcing the government to raise taxes to combat a much bigger budget deficit, a thinktank has predicted. The National Institute of Economic and Social Research (NIESR) said falling birthrates in the UK and a sharp decrease in net migration last year had led it to consider what would happen if this trend continued to the end of the decade. In this scenario the UK population would stop growing at about 70 million in 2030. The latest official figures showed the UK population was 69.3 million...