Set of 4 Royal Mail mint stamps, Scientific Achievements, in Presentation Pack No. 216, issued 5 March 1991. 11.5x22cm. Faraday - Electricity, 22p; Babbage - computer, 22p; Radar - Watson-Watt, 31p; Jet Engine - Whittle, 37p. Designed by Peter Till and John Harwood. With illustrated text enclosure by Neil Ardley.