 The basic rate was reduced from 30% in 1983 to 25% by 1988.The top rate of tax also came down from 60% to 40% in 1988 and the four other higher rates were removed, leaving a system of personal taxation in which there was no rate anywhere in excess of 40 per cent.In 1986, the City of London's financial markets were deregulated in the so-called 'Big Bang'.