Throughout her long and distinguished career, Karen Spärck Jones played a leading international role in the field of information retrieval, an aspect of computer science that was rather disregarded until the arrival of the world wide web made effective searching a vital research priority. Today’s search engines rely on the fundamental research she carried out from the 1960s onwards at the University of Cambridge.

Karen Ida Boalth Spärck Jones was born in Hudders-field, Yorkshire, in 1935, the daughter of chemistry lecturer Owen Jones and Ida Spärck. Her mother, a Norwegian, had worked for her country’s government-in-exile during the Second World War.

After attending a local grammar school, she went up to Girton College, Cambridge, in 1953 to read history before switching to philosophy, or moral sciences as it was called at the time.

She graduated in 1956 and after a brief, unsatisfying spell teaching was invited to join the Cambridge Language Research Unit by its director, Margaret Masterman. This came after an introduction from Roger Needham, a friend from undergraduate days who was studying for a PhD in the Mathematical Laboratory (later the Computer Laboratory).

CLRU was working on natural language processing, looking at how computers could determine the meaning of sentences. Masterman, a former student of Wittgenstein’s, believed that meaning, not grammar, was the key to understanding languages and this view greatly influenced Spärck Jones’s work.

Spärck Jones was trying to build a thesaurus automatically, and as part of her research she transcribed the whole of Roget’s Thesaurus on to punched cards, working closely with Needham on ways to classify information automatically.

She obtained her doctorate in 1964 and her thesis, published as Synonymy and Semantic Classification, remains important even today.

Needham and Spärck Jones married in 1958 and both remained at Cambridge University throughout their careers. However, while Needham rapidly obtained a tenured position and eventually became head of the Computer Laboratory, Spärck Jones had to rely on short-term research fellowships to fund her work until she was awarded a personal professorship in 1999.

In the 1960s she began working in the field of information retrieval, developing a technique known as “IDF term weighting” which has become central to many web-based search tools. In 1968 she moved from CLRU to the Computer Laboratory where she remained for the rest of her life.

An active researcher and prolific writer, Spärck Jones published nine books and more than 200 substantial papers. She described her field as “natural language information processing”, dealing with information in natural languages (ie, ones spoken by people, rather than machines) and information that is conveyed by natural language.

An inspiring teacher and supervisor, she played a full part in the academic life of the Computer Laboratory and the university, and was also a principal adviser to the Alvey research directorate, which funded UK-based research on computing in the 1980s.

In 1999 she organised the extensive celebrations of the 50th anniversary of the ED-SAC computer in Cambridge.

She served as president of the Association for Computa-tional Linguistics in 1994 and was elected a Fellow of the British Academy in 1995. She was a research fellow at Newnham College from 1965 to 1968, a Fellow of Darwin College from 1968 to 1980 and became a Fellow of Wolfson College in 2000, becoming an Honorary Fellow in 2002.

She retired formally from the Computer Laboratory in 2002 but this did not diminish her commitment and she continued to work full-time in the laboratory. Throughout her career she tried to bring more women into computing, arguing that it was too important a discipline to be left to men.

Roger Needham, who had left the Computer Laboratory to become director of Microsoft Research Cambridge, based in the building next door, died in 2003.

Spärck Jones received many honours during her long and distinguished career, including the Association for Computa-tional Linguistics Lifetime Achievement Award and the Institute for Information Scientists research award.

In 2007 she was awarded the Lovelace Medal by the British Computer Society, the first woman to receive it, and also the Allan Newell Award and Athena Lectureship by the American Association for Computing Machinery. With typical foresight she recorded an acceptance lecture before her final illness made it impossible.

Outside computing and linguistics her interests ranged widely. She and Needham built their own house at Coton, just outside Cambridge. She was also an enthusiastic and capable sailor and the couple sailed an 1872 Itchen Ferry Cutter on the East Coast.

She had no children.

Karen Spärck Jones, computer scientist, was born on August 26, 1935. She died of cancer on April 4, 2007, aged 71