As Ellen Meiksins Wood has argued, Thatcherite capitalism was compatible with traditional British political institutions. As Prime Minister, Thatcher did not challenge ancient institutions such as the monarchy or the House of Lords, but some of the most recent additions such as the trade unions. Indeed, many leading Thatcherites, including Thatcher herself, went on to join the House of Lords, an honour which William Ewart Gladstone, for instance, had declined. Thinkers closely associated with Thatcherism include Keith Joseph, Enoch Powell, Friedrich Hayek and Milton Friedman. In an interview with Simon Heffer in 1996, Thatcher stated that the two greatest influences on her as Conservative leader had been Joseph and Powell, who were both "very great men".