Cyril Hilsum’s research into stable liquid crystals and the devices in which they could be used paved the way for the flat-panel television and computer screens that are now ubiquitous in homes, offices and public spaces.
Hilsum, who has died aged 101, was leading a Ministry of Defence team at the Royal Radar Establishment (RRE) in Malvern, Worcestershire, in the late 1960s when Harold Wilson’s Labour government, looking to develop a new generation of miniature radar systems, tasked him with creating flat displays to replace the bulky cathode-ray-tube screens used for traditional radar set-ups.
Realising the key to flat-screen technology was the emerging science of liquid crystals, Hilsum organised a meeting of liquid crystal researchers – and soon realised there was only one person in the room who really understood anything about them: George Gray, from Hull University.
Gray was immediately offered a contract, and began working with Hilsum and Peter Raynes, an optoelectronics expert at the RRE, on fulfilling the government’s brief. By 1972 the three of them had developed a mixture that was suitable for use in screens, made largely of cyanobiphenyls, compounds that remain stable even when heated or exposed to sunlight or ultraviolet light. This gave the resulting screens durability in real-world applications.
Although originally designed to support the RRE’s nascent radar technology, the liquid crystal displays (or LCDs) that used the mixture soon found practical uses elsewhere. While the MoD retained the patents, Hilsum persuaded the chemicals company BDH to manufacture and sell the mixtures under licence, eventually netting the government more than £100m in royalties from their use in watches and calculators, and then later in laptops, tablets and phones.
Hilsum was born in Stepney, east London, to Benjamin and Ada, who were street traders. A bright boy who had learned to read proficiently by the age of three and spent hours dismantling toys to see how they worked, he went to Raine’s Foundation school in Bethnal Green, after which, during the second world war, he won a scholarship to University College London, which had been evacuated to Bangor in north Wales.
He graduated with a degree in physics in 1945 and later a PhD, meeting fellow student Betty Cooper at UCL and marrying her in 1947. He and Betty, who became a teacher, were keen Labour party supporters, and after the war would attend Winston Churchill’s meetings in order to heckle him.
After an initial spell working for the MoD in central London immediately after the war, he moved in 1947 to the Admiralty Research Laboratory in Teddington, where he met Alan Turing, who worked at the nearby National Physical Laboratory, and whom he once beat at chess. By 1950, aged 25, he was leading a team studying military uses for infrared light, based at the Services Electronics Research Laboratory in Baldock, Hertfordshire.
Hilsum joined the RRE in 1964 to carry out research into gallium arsenide, a semiconductor material that handles high-frequencies, and on the development of radar, transistors and light-emitting diodes (LEDs). In fact his work on semiconductors was as significant as that on LCDs, and included helping to develop infrared lasers that now underpin fibre optic telecommunications.
He was also instrumental in developing the Gunn diode, a high-frequency oscillator that generates microwave signals used in motion detectors and proximity sensors, including police radar speed guns – sometimes to his disadvantage, given that he was a fast driver. In tandem, his work on developing miniature radar systems led to Claribel, a device for detecting the trajectory of a bullet, which was used to locate snipers in Northern Ireland during the Troubles.
In 1974 Hilsum became the UK’s chief scientific officer, the highest rank for a scientist in the civil service and a position he held for two decades before accepting the role of chief scientist, and later research director, at the General Electrical Company’s Hirst Research Centre in Wembley, north west London. Always a promoter of women in sciences, at GEC he insisted his department hire equal numbers of both sexes.
After retiring from GEC in 1995, Hilsum served as president of the Institute of Physics from 1988 to 1990 and was appointed CBE in 1990 for services to the electrical and electronics industry.
He was a fellow of the Royal Society and, in addition to his CBE, won various awards, including the Faraday Medal and in 2007 the Royal Society’s Royal Medal “for his many outstanding contributions and for continuing to use his prodigious talents on behalf of industry, government and academe”. The British Liquid Crystal Society awards the Cyril Hilsum Medal annually for the best contribution to liquid crystal technology.
In later years Hilsum built a laboratory in his house in Pinner, Middlesex, where, aged 97, he came up with his final invention – an ink containing sensors to conduct electricity – earning him the last of more than 70 patents. He ascribed his longevity to red wine and chocolate, and was a lifelong reader of the Guardian.
Betty died in 1987, and one of their daughters, Karen, also predeceased him, in 1997. He is survived by their other daughter, Lindsey, international editor for Channel 4 News, and a grandson, Alexander.
• Cyril Hilsum, physicist and inventor, born 17 May 1925; died 23 September 2026
