Margaret Thatcher tendency to override collegiate opinion, contributed to discontent within her party. Thatcher removed Geoffrey Howe as Foreign Secretary in July 1989 after he and Lawson had forced her to agree to a plan for Britain to join the European Exchange Rate Mechanism (ERM). Britain joined the ERM in October 1990. On 1 November 1990, Howe, by then the last remaining member of Thatcher's original 1979 cabinet, resigned from his position as Deputy Prime Minister, ostensibly over her open hostility to moves towards European Monetary Union. In his resignation speech on 13 November, Howe commented on Thatcher's openly dismissive attitude to
Historical rankings of Prime Ministers of the United Kingdom using a 0 to 10 scale, where 0 meant highly unsuccessful and 10 meant highly successful. Overall, MPs rated Margaret Thatcher as the most successful post-war Prime Minister, just ahead of Clement Attlee. With the exception of Edward Heath, who was judged more favourably by Labour MPs than by Conservatives, evaluations were split along party lines: Tory MPs tended to consider Conservative prime ministers to be more successful than did Labour MPs, and Labour MPs generally gave Labour prime ministers higher scores than did Conservative MPs. In October 2016 the University of Leeds, in conjunction with Woodnewton Associates, surveyed 82