Catherine McColl

Catherine McColl, who has died aged 97, was a Glasgow grandmother who took Scotland's biggest council to court over its plan to add fluoride to tap water – and won.

Her campaign led to one of the longest civil actions in the country's history and its outcome was hailed by her supporters as a victory of the ordinary citizen over the powers that be. To her opponents, however, it was a missed opportunity to improve dental health in a region which had one of the worst records of tooth decay in Europe.

In 1979 Strathclyde Regional Council had by a single vote passed a motion to put fluoride into the water supply as a counter measure against tooth decay. However, the local authority had not bargained for the formidable opposition presented by Mrs McColl.

She launched a highly charged campaign against the move and applied for an interdict to stop the council, claiming its action was unsafe, ineffective and illegal.

The case went to the Court of Session in Edinburgh, the highest civil court in the land. In a 300-page judgment, published four years later, Lord Jauncey ruled that Strathclyde had exceeded its powers.

Despite the fact that the judge rejected all the major medical arguments against fluoridation, his ruling stopped the council's action in its tracks and, to this day, the chemical has never been added to Scotland's water supply.

Cathy McColl was born in the Kinning Park area of Glasgow. Her parents both died when she was young. She left school and went to work on the shop floor of the factory which produced Creamola Foam. A committed Communist, she became an active trade union official and led a strike which ended in a wage rise for the workforce.

During the Second World War she left the city to work as a land girl, returning to her old job in 1945. It was through her involvement with the Communist Party that she met her husband, Robert McColl, whom she married in 1947. The couple had a daughter, Rena. Mr McColl died in 1964.

A highly effective community activist with an acute sense of social justice, she came to the attention of the Scottish public when she launched her anti-fluoride campaign. She faced strong opposition from the medical establishment, including the British Dental Association, the BMA and the World Health Organisation.

The ensuing court case, which ran from 1980 till 1982, became the longest and most expensive legal action of its time. Expert witnesses from as far afield as Australia and the US came to Scotland to give evidence. The court sat for 201 days and heard 143 days of evidence. It cost more than £1 million. Mrs McColl's costs were covered by Legal Aid.

Aged 67 when the legal proceedings began, she had no teeth of her own. Giving evidence on the first day, she described fluoride as "a witch's brew".

Lord Jauncey had to plough through more than one million words of evidence before reaching his judgment. The case so dominated his schedule that, when his wife gave birth to their daughter during the proceedings, a court official jokingly suggested he should call the child "Fluorina". He demurred, choosing instead to call her Cressida.

After her success, Mrs McColl, who lived in Caledonia Road, Gorbals, continued to campaign on other issues affecting her community, including water privatisation, the poll tax and hospital closures. She was also chairwomanof Gorbals Community Council.

Throughout her life she had been a gifted painter of watercolours and, in her 70s, she took formal art classes. She also taught herself Gaelic. Suffering ill health, Mrs McColl had recently moved to a care home.