Eirlys Roberts was a leader of Britain’s consumer movement and editor of Which? for 15 years. Lord Young of Dartington, the social innovator and initiator of the Consumers’ Association, once referred to her as “the most considerable figure thrown up by the British consumer movement”. As head of research at the CA, the historian and evaluator of its work, and as editor of CA’s magazine, Which?, she did more than live up to that description. Her books included Consumers (1966) and Which? 25: Consumers’ Association, 1957-82 (1982), marking the organisation’s 25th anniversary.

Above all, it was Roberts who preserved and developed the standards of what has become a powerful public service institution. As the former CA director, Peter Goldman put it: “The legacy endures, for no matter how much Consumers’ Association alters, the golden rules of the higher journalism hold good. The information we provide must always be accurate. The way it is communicated must always be accessible. The conclusions we draw from it must always pay regard to the public’s interest exclusively.”

Roberts and several of her senior colleagues had all read classics at school and university, which she claimed was the accidental reason for the simplicity and clarity of the language used. “A good teacher will require,” she wrote, “that a Latin or a Greek text shall be translated in Anglo-Saxon words — how else will they know that a pupil who translates mare caeruleum as ‘cerulean sea’ knows what colour that is?

“So the Which? project officers were required to use concrete nouns, not abstract ones, the active not the passive voice, short sentences, short paragraphs, and short Anglo-Saxon words.” Her own column in the magazine typified both this style and the campaign for consumers’ right which it served.

Eirlys Rhiwen Cadwaladr Roberts was born in 1911, a Londoner with a Welsh doctor father (and grandfather) and a Scottish mother who lived to more than 100. Educated at Clapham High School and Girton College, Cambridge, where she read classics, she afterwards became classical adviser to Robert Graves. In the preface to I, Claudius he wrote, “with help towards classical correctness, I have to thank Miss Eirlys Roberts”.

She lived in Majorca for a time with Graves, Laura Riding and her own partner, the polymathic Jacob Bronowski, who wanted to marry her. But she went back — still single — to London, learnt her trade as a journalist and it was not until 1941 that she married John Cullen. Although the marriage only lasted a few years, she remained fond of him and retained her married name in private life.

Roberts had a good and interesting war in military and political intelligence, but the most exciting period was postwar, 1945-47, when she worked in Albania for the United Nations Relief and Rehabilitation Administration, a dangerous time in a dangerous country. Back in England, she joined the Treasury and stayed in the information division for ten years.

As part of her civil service brief as a press officer, she had taken over from her friend the novelist Marghanita Laski the writing of consumer articles for The Observer. At this time, Michael Young was being encouraged by Dorothy Goodman, a young American in London, to start a British equivalent of the Trans-Atlantic Consumers Union, well established in the US. Young’s group advertised for a full-time director, who was also to be editor of the magazine (they could not afford both).

The journalist Peta Fordham got the job and edited the first issue of what by now had been christened Which? CA tested a number of products; electric kettles, sunglasses, aspirins, cakes baked from cake mixes and non-iron cotton clothes (not, sadly, shirts. The examples were eaten by reindeer while the testers were on holiday in Lapland).

The results were then published, a launching press conference was packed with journalists and CA’s temporary headquarters, a tiny former garage in Bethnal Green, was swamped “with envelopes containing 10-shilling notes — subscriptions to the new magazine. The council did not know what had hit it.”

But as Roberts pointed out: “What had hit them was people’s need. Here was something which promised to be a guide telling them precisely what to do when faced with the intolerably confusing choice between competing brands, so they could be certain of making good use of their money, of getting the best value for what they spent.”

The magazine had no advertising, and no money from industry and government, only from its 10,000 subscribers. That number rapidly increased.

Eirlys took over as editor from Fordham, who resigned after the first edition, and she steered the magazine and its spin-offs for the next 15 years. In the process, Roberts led a revolution in popular attitudes towards products. CA supported research, testing and reporting; it spread its wings over a vast territory: Which? Motoring, Which? Money, Which? Handiman, Which? Holiday, Gardening from Which?, Which? Wine Guide. In addition there were television and radio programmes (among them Money-Go-Round on Thames TV, and Value for Money on BBC Radio, on which Roberts was consultant and contributor), advice centres, supplements on contraceptives, estate agents, London stations and the elderly.

The standards that she insisted upon, the intellectual rigour that she imposed, and “a tough intelligent Celtic charm” as Goldman put it, “drew out of those who worked for it \ more than they thought they had in them”.

Roberts was appointed OBE in 1971 and when she retired from CA in 1977, after four years as deputy director, she was advanced to CBE.

But she was by no means retired from semi-public life. She was at various times a member of the Royal Commission on the press, chair and chief executive of Erica, the European Research Institute for Consumer Affairs, the first chief executive of European consumer organisations, and chair of the Environmental and Consumer Protection Committee of the EEC, spending much of the year living in Brussels.

But her home in Lloyd Square, Clerkenwell, was a happy and lively centre for friends, and she led a very full social life. Walking and detective novels were her private passions.

Eirlys Roberts, CBE, editor of Which?, 1958-73, was born on January 3, 1911. She died on March 18, 2008, aged 97