It resulted in 341 cases of typhoid (43 fatal), and it caused considerable local discontent leading to a media campaign and a public inquiry.

Coupled with issues around the co-operation between the medical officers and the administrators of the Borough, three coincidental events were blamed; changes to the well structure by repair work, the employment of a new workman who was an unwitting carrier of typhoid, and failure to chlorinate the water.

Subsequently, an integrated water supply and sewage disposal system was installed at Croydon, twelve miles south of London, one of the first towns to have one, when its population was around 20,000.

[7] Worrying levels of the bacteria E. coli in the Addington well water resulted in regular chlorination from 20 July 1936, but without any continuous record of its use.

Both the reservoir and well waters were supposedly tested monthly, until the end of April 1937, when for no explainable reason except by "mere oversight", it stopped.

[1] From 16 October 1937, unknown to either the Borough engineer, Charles Boast, or Croydon's medical officer of health, Oscar Holden, this raw untreated water began to be pumped into the public supply.

[1] The origin of the illness was initially thought to be infected shellfish from the European mainland, as the earliest case in 1937 presented mid-October with a history of travel to France.

[12] His father Charles Rimington, who worked for the Bank of England, conducted his own investigations, and by visiting and questioning those that he personally knew and that were affected, he deduced that the source of the outbreak must be the water supply.

[6][10] Dissatisfied with Holden's explanations, the residents formed the South Croydon Typhoid Outbreak Committee (SCTOC), chaired by Charles Rimington.

The source of the illness remained a mystery until 3 November 1937, the day after Holden requested the aid of Ernest T. Conybeare, the Ministry of Health's expert on typhoid, who mapped out the cases and matched them with the water supply using traditional epidemiological methods.

[3][6][11][12] The outbreak caused considerable local discontent and representatives of the SCTOC acted to lead a media campaign and initiate a public inquiry.

[5][6] Murphy later replied to the Minister of Health; The immediate cause of the outbreak was a portion of the public water supply becoming infected by the typhoid bacillus.

How that well became infected is a question that cannot be answered with absolute certainty, but all the circumstances and probabilities point so strongly in one direction that I feel justified in coming to a definite conclusion on the subject.

[5][1] Holden was however, unaware of the cessation of chlorination while works were being carried out,[6] and he was accused of not notifying local doctors earlier.

[5][6] A combination of factors were concluded to have caused the incident, including the repair works on the well, the worker who was a carrier of typhoid and the water supply not being chlorinated.

[10] The cases attracted national media attention, as was reflected in the number of scrapbooks of newspaper articles contained in 17 volumes collected by Walter Monckton and the Croydon Corporation.

[21] In The Classical Quarterly in 1979, the typhoid outbreak of 1937 was described as the "most recent serious event of this kind to take place in this country",[22] typical of "when a large population draws its water supply from a central source".