This image has been provided by David Muggleton.

The 'Ilford Transparency Viewer' for 2"x2" (35mm or 4x4cm) slides was being marketed by mid-1963. Its plano-convex lens gave a magnification of 1.5x. The box logo shown here has the Ilford 'sunburst' symbol which appeared in 1965, so this example must date to 1965 or later. It cost £1.4s.6d (£1.23p). It worked off 2xUII ('C' type) batteries. The viewer price included a bulb but excluded the batteries.