Molly Stiles thought she would just be serving tea to village parents wanting to keep their small school open. Twenty years later, she had almost single-handedly ensured that no small-school closure anywhere in the country would go unchallenged.

Molly Kettle was born in south London in May 1932. As a war child, she was evacuated repeatedly: she attended at least seven different schools. In later life, she would say that this gave her an acute awareness of how good or bad schools could be.

It was this awareness that motivated her decision to train as a teacher. Working as a supply teacher in Bromley after the war, she took chorus line parts in amateur dramatic productions. It was during one such production that she met Raymond Stiles, a fellow new teacher. They married in 1957; their three children, Lindsay, Dominic and Martin, followed shortly afterwards.

The couple moved to Norfolk in 1964, when Ray was appointed head of a two-room rural school. The village schoolmaster and his wife were, along with the policeman and the postmaster, key figures in their new community.

This sense of tightly knit community became increasingly important to Mrs Stiles. She was fascinated by local history, and believed strongly in the continuity of rural life. The school formed a vital part of this: it inculcated a sense of belonging in children from an early age.

Then the 1967 Plowden Report was published, encouraging the amalgamation of smaller primaries into larger schools. Nine years later, a group of Garvestone locals, outraged this this would affect their schools, met in a village hall. Mrs Stiles went along in her capacity as schoolmaster’s wife: she assumed she would be making tea and handing out biscuits. She emerged secretary of a new organisation: Dove, the Defenders of Village Education.

From then on, saving small schools became her full-time job. When the family moved to a new house in Norwich in 1977, their dining-room was filled with piles of correspondence, ministerial papers and mail drops.

Gradually, villagers from other communities across the country began to join Dove. Then, in 1978, a group of parents in Staffordshire contacted Mrs Stiles, thinking she might prove a useful ally in their battle against the council. She immediately called a national meeting of all those interested in preserving small schools: the Victorian schoolhouse was full to capacity. In an impassioned speech, she argued for a national organisation to prevent further closures. And thus the National Association for the Support of Small Schools (NASS) was born, with Mrs Stiles at its head.

She was not a banner-waving activist; instead, her strength was behind-the-scenes organisation. “I can’t save your school,” she would repeatedly tell villagers. “I just give you the ammunition - you have to want to save it yourselves.”

Described by NASS colleagues as “a human dynamo”, she would spend her days making phone calls, writing letters and speaking on local radio. She was regularly seen riding her bicycle across the Norfolk plains, her homemade cloak flapping in the wind behind her.

Her greatest asset, however, was her ability to identify those in positions of relevant power, and cultivate their acquaintance. For years, she was to be found at the Conservative party conference: she was a consummate networker, and would spend the event handing out leaflets and pigeon-holing influential figures (on one occasion, she bought TV presenter Robin Day a box of matches, because his had run out).

As a result, she punched above her small school weight. Ministers regularly agreed to meet her, and made sure to do their homework before they did: she relished the opportunity to catch them in an error. And every NASS conference would include a star turn, from Clement Freud to then education secretary Keith Joseph - a feat her successors cannot imagine emulating.

In the 1990s, she bought and renovated a listed building in the centre of Norwich. At this point, Ray finally convinced her that it might be time to retire and relax.

“There’s no point burying me,” she had always told her family. “Pack me off for medical research.”

It was an unwittingly prescient suggestion: she went on to develop a rare form of dementia. Research on her brain is now being conducted at University College London.