Harold Wilson was Prime Minister for almost eight years - the longest period spent in office this century until Mrs Thatcher. He fought five general elections and won four. While he was at Number Ten, Wilson held together the unruly elements of Left and Right in a Parliamentary party often at odds with itself, challenged the power of the trade unions, faced repeated economic crises and a devaluation, was abandoned by his own Cabinet and had to concede defeat. His period in office was one of the most momentous and controversial of the country's post-war history. His resignation took almost everyone by surprise and rumours still circulate about its cause. Philip Ziegler is the first historian to have access to Harold Wilson's personal archive, including much official documentation that will not become available for a decade or more. Although he has the blessing of his subject, Ziegler has remained totally independent. Philip Ziegler has written biographies qf Mountbatten, Edward VIII and Diana Cooper.