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March 19, 2026

Professor Sir Charles Anthony Richard (Tony) Hoare FRS FREng, Honorary Fellow of Kellogg College, passed away on 5th March 2026 at the age of 92. He was one of the most influential figures in the field of computer science. In particular from a Kellogg perspective, he was instrumental in establishing the Professional Master’s Programme that forms the largest cohort of students in the college.

Tony was born in Colombo in (then) Ceylon in 1934. After studying Classics and Philosophy (known as “Greats”) at Oxford, he did his National Service in the Royal Navy, where he learnt Russian. He returned briefly to Oxford in 1958 for a postgraduate certificate in Statistics, then spent a couple of years as an exchange student in Moscow, studying machine translation. He returned to the UK in 1960 to the computer manufacturers Elliott Brothers Ltd, notably leading development of a compiler for the language Algol60. He was appointed Professor of Computing Science at Queen’s University Belfast in 1968, then returned to Oxford in 1977 to lead the Programming Research Group in what was then the Computing Laboratory. He remained in that post until retirement in 2000, at which point he joined Microsoft Research in Cambridge.

Tony made many seminal contributions to computing. To undergraduates, he is best known for his Quicksort algorithm, invented while in Moscow and winning sixpence in a bet with his manager at Elliotts when it did indeed turn out to be quicker than the best alternative. Programming language researchers know him best for Hoare Logic, an axiomatic basis for proving programs correct; in 1980 he received the Turing Award – the computing equivalent to the Nobel Prize – for “fundamental contributions to the definition and design of programming languages”. Professional developers may regret his invention of null references, “because it was so easy to implement” – Tony famously went on to call this his Billion Dollar Mistake, on account of the bugs it enabled. At Kellogg, we thank him for his groundbreaking work on the mathematical notations Z and especially CSP for specifying software systems, which lead to collaborations with IBM and thence to the MSc in Software Engineering. He was elected an Honorary Fellow in 1998.

Tony had excellent scientific taste. As a member of IFIP Working Group 2.1 designing the successor to Algol60, he famously co-authored a Minority Report as an addendum to the Algol68 Report, arguing that it was too complicated and a “failed experiment”. His counter-proposal Algol-W with Niklaus Wirth had much greater impact. Here is one of the aphorisms he has left us with: “There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies.”