He provided the martyrologist John Foxe with letters of some who had died for the faith. Mter Elizabeth's accession he sought to further the cause. He was a committed Protestant who remained in London during the Marian reign, being active in the underground church in the metropolis and providing aid to fellow believers in prison such as John Careless.

William Winthrop (1529–1582) was a member of the Clothworkers Company and long time resident of the parish of St. Varying concentrations of dolomite account for variations in the Mg content of London Clay groundwaters and for the distribution of a number of historic purging waters around London. The mineralogy of the clays suggests that pyrite oxidation in the weathered zone forms acid solutions leading to the dissolution of carbonates, particularly dolomite. The waters were derived from thin sandy horizons within the London Clay Formation and were characterized by high concentrations of Mg and SO4. The waters continued to be used by local people for the following 200 years but never achieved national fame, and the source had disappeared by the 1920s. Epsom Salts were produced at Shooter's Hill around 1700 and undercut in price those from Epsom and Acton to the west of London. The probable author of this has been identified as Nathaniel Hodges, a physician who remained in London treating the sick during the plague year of 1665. They were promoted through an anonymous broadsheet, a single copy of which is held by the British Library. In around 1670 purging mineral waters were discovered on the western slopes of Shooter's Hill near Woolwich, to the east of London.

Besieged by financial problems in later life, his practice began to fail in the 1680s and he eventually died in a debtor’s prison. Hodges’ approach to the treatment of plague victims was empathetic and based on the traditional Galenic method rather than Paracelsianism although he was pragmatic in the rejection of formulae and simples which he judged from experience to be ineffective. His daily precautions against contracting the disease included fortifying himself with Théodore de Mayerne’s antipestilential electuary and the liberal consumption of Sack. Prominent as one of a handful of medical men who remained in London during the time of the Great Plague of 1665, he wrote the definitive work on the outbreak. Educated at Westminster School, Trinity College Cambridge and Christ Church College, Oxford, Nathaniel established himself as a physician in Walbrook Ward in the City of London. Nathaniel Hodges was the son of Thomas Hodges (1605–1672), an influential Anglican preacher and reformer with strong connections in the political life of Carolingian London.

The plague doctor 1665