1956 was a key year for Alloway as a critic and theorist. In that year there were a number of important exhibitions that represented the tendencies Alloway supported: American action painting, art autre, and human images influenced by popular culture. There was the chance to reassess the relevance of Dada and to continue to attack Herbert Read. And Alloway's plural view of culture enabled him to write about not only art, but also graphic design, photography, advertising, science fiction illustration, robots, product design, and architecture. 1956 was important because a combination of developments occurred in art, as well as the working through of his IG-related thinking about an inclusive model of culture and art's place within it. The model begins to come into focus at the seminal This Is Tomorrow exhibition, held at the Whitechapel Art Gallery in London in August and September.

The idea for the exhibition had originated in 1950 when Paule Vézelay and members of Groupe Espace proposed a Constructivistcum- Le Corbusier-influenced exhibition. A tension arose between the Constructivist-Modernist members, and some of the IG sympathizers, including Alloway and Banham. The exhibition itself continued the tension between unambiguously Modernist combinations of architecture, sculpture and painting as integrated abstract, environmental form, and alternative visions and preoccupations involving IG regulars including Hamilton, McHale, Paolozzi, the Smithsons, Henderson, del Renzio, and Alloway.

The exhibition featured twelve groups, each of three members— notionally a painter, sculptor, and architect—with each group presenting an environmental exhibit relating to the title of the exhibition. Three of the groups in This Is Tomorrow expressed strands of the IG's thinking. The most celebrated group is Group 2 which comprised Richard Hamilton, John McHale, and the architect John Voelcker whose environment combined perceptual ambiguity with imagery from contemporary mass media and popular culture including a life-size photograph of Marilyn Monroe; a cardboard cut-out of Robby, the robot from the science fiction film Forbidden Planet (1956); and a juke box which pounded out the top twenty hits of the day. “Tomorrow” was expressed in terms of sensory bombardment, appealing domestic technology and the “expendable ikon.” The second collaboration was Group 6's Patio and Pavilion which the Smithsons, Eduardo Paolozzi, and Nigel Henderson worked on together.