For the past four years, the James Webb space telescope has been returning stunning images of stars and galaxies that formed in the early universe. Parked in orbit a million miles from the Earth, the observatory is an extraordinarily sophisticated machine that shares a special engineering heritage with a swelling number of modern devices, from mobile phones to medical scanners and turbine blades.
All are products of precision engineering, a discipline that blends the traditions of surveying, navigation, astronomy and time-keeping to create the technology that underpins our lives today. And one of its prime exponents was Patrick McKeown.
McKeown, who has died aged 95, wrote the “11 principles of machine design” that were a distillation of everything he had learned about accuracy, stability and error correction in mechanical systems, and that have become the bedrock of precision engineering across the world. In 1968, he used these principles to help launch a world-leading unit dedicated to the field at the Cranfield College of Aeronautics, which is now Cranfield University.
The ultra-precision tools that were developed at the Cranfield Unit for Precision Engineering (CUPE) under his guidance are capable of measuring and shaping objects to atomic-level accuracy and are used for myriad different purposes today: to make MRI and CT scanners; to create huge display screens that are installed at Wembley, Twickenham and other stadiums; and to use their billionth of a metre accuracy to manufacture the tiny integrated circuits that run our phones and laptops.
However, their contribution to the James Webb space telescope (JWST) is probably the most exciting example of the breakthroughs inspired by McKeown. Outside Earth’s atmosphere, space telescopes give unprecedented, clear views of the heavens but are hard to maintain. The Hubble space telescope, the JWST’s predecessor, required five separate $500m shuttle missions so astronauts could service it.
Precision engineering changed that by dispensing with the need for humans. After its launch in 2021, the JWST’s hexagonal-shaped mirror segments – designed with an accuracy of one thousandth of a human hair’s diameter – unfolded automatically to form a seamless single, huge mirror. Crucially, the lion’s share of the high-precision mirrors for one of the JWST’s main detectors, the Mid-Infrared Instrument, were manufactured at McKeown’s CUPE.
As Paul Shore, former head of engineering at the National Physical Laboratory, said: “Look up to the stars, understand that a million miles from Earth the James Webb space telescope is looking out into the universe, and it’s doing so with mirrors made at Cranfield using a Pat McKeown ultra precision machine.”
The renown of McKeown was remarkable, as testified by the engineer Dame Helen Atkinson, a deputy vice-chancellor at Cranfield. “I visited an engineering lab in Singapore a few years ago and everyone there wanted to know about Pat, even though this was on the other side of the world and he had retired a decade earlier,” Atkinson said. “He was one of the greatest precision engineers in the world.”
Born to Bob McKeown, an aeronautical inspector, and Gus (nee White) in Cricklewood, Middlesex (now part of Greater London), Pat experienced a childhood shaped by the vicissitudes of the second world war. Having moved to Coventry for Bob’s work, the family survived the blitz there in 1940 and was relocated to Prestwick, in Scotland. There he oversaw the receipt of American lend-lease aircraft and immersed his son in a world of engines and precision engineering, including a flight in the tail turret of a Liberator bomber over the Firth of Clyde. “A truly memorable experience,” McKeown later recalled.
After the family returned to England, Pat attended Bristol grammar school, where he excelled at rugby and athletics. While in Bristol, he met Mary Heath, whom he married in 1954. National service in the Royal Engineers was followed by a student apprenticeship at the Bristol Aircraft Company, where managers encouraged him to attend the College of Aeronautics at Cranfield, and he gained an MSc there in 1956.
After working for more than a decade for the Swiss metrology company Société Genevoise d’Instruments de Physique (GSIP) – where he developed methods for defining and improving the three-dimensional accuracy of machine tools – McKeown returned to Cranfield to help set up its precision engineering unit, using funding from Harold Wilson’s “white heat of technology” programme.
The machines built by his team achieved unprecedented levels of accuracy that could be measured in billionths of a metre. At a time when the UK’s manufacturing was faltering, McKeown bucked the trend, however, walking into the offices of IBM, Kodak and 3M and emerging with lucrative contracts. Thanks to these, CUPE began to expand.
After retiring from Cranfield in 1995, he was the driving force behind the creation of the European Society for Precision Engineering and Nanotechnology (Euspen), which he founded and presided over in 1999, and which held its 26th international conference this year. He was elected a fellow of the Royal Academy of Engineering in 1986.
Other honours included being apppointed OBE in 1991, the Faraday medal, the Georg-Schlesinger Preis, and lifetime achievement awards from engineering societies in the US, Japan and Europe.
Pat was also a patron of Humanists UK and a committed humanist who believed people could live ethical, meaningful lives guided by reason and evidence rather than religion, and he campaigned vigorously for a secular state.
He is survived by Mary, their three sons, Jonathan, Jeremy and Nick, nine grandchildren and six great-grandchildren.
• Patrick Arthur McKeown, engineer, born 16 August 1930; died 10 February 2026
