'Tunnel' reflects Tucker's conviction that a sculpture should be a thing rather than an image, asserting itself as 'a direct physical and visual fact'. It should be in the world of recognisable objects but also separate from them, being unfamiliar and surprising. In 'Tunnel' this ambivalence is achieved through its articulation of space. Although abstract, its scale, form and materials evoke the familiar experience of habitable space. The way Tucker encloses a void and invests this with human significance shows the influence of Gonzalez's 'Head called 'The Tunnel'' (in Gallery 29). The structural innovations of 'Tunnel' had significance for the next generation of sculptors, in particular Richard Deacon.