A no-deal Brexit could slam the brakes on the UK’s economic growth, wiping out Chancellor Philip Hammond’s hopes of boosting public spending, a think tank has said. If the UK fails to reach a withdrawal deal with the EU and moves on to World Trade Organization (WTO) rules next March, GDP growth can be expected to slow sharply from 1.4% this year to 0.3% in both 2019 and 2020, said the National Institute of Economic and Social Research (Niesr).