Answer
John Major succeeded Geoffrey Howe as Foreign Secretary. Howe, who had served as Foreign Secretary since 1983, resigned in 1989 due to disagreements with Prime Minister Margaret Thatcher over her opposition to European integration. Major, who had previously held the positions of Chief Secretary to the Treasury and Chancellor of the Exchequer, was appointed Foreign Secretary by Thatcher and served in that role until 1990, when he became Prime Minister.