He was the author of the phrase ‘too clever by half’ to describe the many people who were not as stupid as he

From Small Wars, Faraway Places by Michael Burleigh. Page 287.

In the event, with Eden ill and Churchill felled by a stroke, the negotiations were concluded by Lord ‘Bobbety’ Salisbury, who took over the Foreign Office between late July and early October 1954. He was the author of the phrase ‘too clever by half’ to describe the many people who were not as stupid as he, but he had some help from the CIA station in Cairo, which helped to distinguish between what was posturing and what substance in the Egyptian negotiating stance. The final terms agreed that British forces were to evacuate the Suez bases, although 4,000 technicians would keep the bases in readiness should the troops have to return to defend Egypt and other states of the region from Soviet attack. The new treaty was to run for seven years, until 1961.