SOME years ago, Jean Thompson was on a river cruise down the Ouse. The skipper was delivering a commentary on all the famous riverside landmarks. As the boat sailed by what is now the Moat House Hotel, Mrs Thompson hoped to hear a few words about her illustrious forebear, Dr John Snow, who had been born near the site.

Dr Snow was certainly worthy of comment. A pioneer of Victorian medicine, he is still revered today in medical circles. This was the man who introduced anaesthetics to a grateful Queen Victoria in childbirth. More than that, he made a discovery that marked the beginning of the eradication of cholera from Britain.

To Mrs Thompson's disappointment, the boat slipped by the hotel without so much as a word about the good doctor. But she was not surprised. York is largely unaware about this remarkable former citizen.

So when she uncovered some more cuttings about Dr Snow recently, she got in touch with Yesterday Once More. "I'm convinced the people of York would be interested to know of John Snow, especially the modern-day medical profession," she said.

The documentation was gathered by Mrs Thompson's uncle, the late George Sims. A joiner by trade, he was a keen historian, teaching archaeology at the technical college.

While researching his family tree, Mr Sims came across the remarkable Dr Snow. Learning of his achievements he successfully campaigned to have a plaque erected to the good doctor in 1983 at what was then the Viking Hotel on North Street.

Dr Snow's story starts on North Street. He was born there in 1813, the first of nine children of William and Frances Snow. This was one of the poorer areas of York. North Street was prone to flooding and badly drained.

William Snow had begun his working life as a labourer, working in a York coal yard. He was clearly an astute and industrious man. According to a biography of Dr Snow on the University of California, Los Angeles (UCLA) school of public health web site, he moved from labourer to horse-drawn carriage driver, delivering to riverside warehouses.

Working hard and saving carefully, he bought five houses in Queen Street during the 1820s and 1830s, renting them out to support his large family. William later became a farmer in Rawcliffe.

Religion was central to the Snow family life. They attended All Saints Church regularly.

William and Frances were determined to give their children the best possible start in life. As soon as he was old enough, John attended school, most likely one of the four charity or private schools near his North Street home.

According to an appreciation of Dr Snow's life, written by his friend Sir Benjamin Ward Richardson in 1887, a copy of which is housed at York Reference Library, "he was fond of the study of mathematics, and in arithmetic became very prominent".

Keen to pursue a career in medicine, at 14 he became an articled pupil to William Hardcastle, a Newcastle surgeon.

Three years later, he turned vegetarian. "He was a noted swimmer at this time, and could make head against the tide longer than any of his omnivorous friends," wrote Sir Benjamin. "At or about the same time that he adopted his vegetarian views he also took up the temperance cause."

Dr Snow's championing of the teetotal lifestyle was recalled after his death by his brother Thomas, a clergyman. In a letter to the British Temperance Advocate in 1886, the Rev Snow described how the future doctor returned to York at the age of 23 and "his very first walk into the heart of the city was taken with the express object of inquiring into the means of introducing teetotalism".

He went on to play a leading role in establishing the York Temperance Society.

But it was not in his home city but in London that Dr Snow was to become justly revered. According to a lecture given by Sir Ian Fraser in 1968, entitled John Snow And His Surgical Friends, he made the journey on foot.

The mammoth trek was made "even longer and more interesting by taking in Liverpool, North Wales, South Wales and Bath before reaching London itself," he said.

"This was in the summer of 1836 and by October of that year, at the age of 23, he sat on the benches of the Hunterian School of Medicine in Windmill Street".

After qualifying he set up his practice in Frith Street, Soho, London. In 1846 came the discovery of ether, the first real anaesthetic: for the first time patients did not have to be awake while under the surgeon's knife.

Dr Snow refined its application and apparatus, making it much more effective. He became so celebrated that Queen Victoria called on his services during the birth of Prince Leopold. He administered chloroform, which had replaced ether, and did the same when Princess Beatrice was born.

Suddenly, the convention that painkilling drugs should be avoided during labour (it was thought better if women suffered) vanished.

Dr Snow was always loyal and discreet, saying only: "Her Majesty was a model patient."

In 1854, a terrible outbreak of cholera killed 600 people within a quarter of a mile. Most people believed it was caused by bad air, or miasma. But Dr Snow was not so sure. He believed the illness was ingested, and suspected the water supply.

This belief grew when he realised most of the people who died lived near the same water pump in Broad Street.

When he discovered that deaths elsewhere in London could be traced to that same pump, Dr Snow revealed his findings. The pump handle was removed and the cases immediately diminished.

Further investigation found that the water supply to the pump was most likely contaminated by sewage. In the words of Adam Hart-Davis, presenter of BBC2's Local Heroes, "the cumulative effect of his Dr Snow's meticulously gathered data was devastating - and was the beginning of the end for cholera in Britain".

John Snow had never enjoyed robust health. He suffered tuberculosis of the lungs and renal disease. He died in 1858, aged 45. He was buried in Brompton Cemetery in London. Soon afterwards his friends erected a monument in the cemetery, with an inscription which included the words: "In remembrance of his great labours in science and of the excellence of his private life and character." The original was destroyed in a wartime air raid, but a replica was created in 1954.

Dr Snow left a legacy of 82 books. A pub named after him can be found on Broadwick Street, formerly Broad Street, in London. And York has that plaque.