Jan Ingen Housz was a Dutch physician and scientist. He worked in London popularising the practice of variolation, inoculating against smallpox by infecting patients with small quantities of the virus. In 1768 he travelled to Vienna to successfully inoculate the Austrian royal family. In 1779 he published his seminal article, “Experiments Upon Vegetables, Discovering their Great Power of Purifying the Common Air in Sunshine, and of Injuring It in the Shade and at Night.”

Ingen Housz was a friend of Joseph Priestley, who had previously demonstrated plants’ restorative effects on the air around us and its essential importance to animal life.  Ingen Housz made the connection between sunlight and this restoration, a process that became known as photosynthesis; the process whereby green plants in sunlight absorb carbon dioxide and release oxygen.

Ingen Housz gained the friendship of the marquis of Lansdowne and was a regular visitor to Bowood near Calne. He conducted some of his experiments in the same laboratory there where Joseph Priestley had, a few years earlier, discovered oxygen. He also frequented Bath, then a major centre for medicine.

Ingen Housz died at Bowood at the age of 68. His wishes, “to be buried quietly, with propriety and without show” within “the church of the parish in which I will die”, were respected. His funeral took place in St Mary’s church on Monday 9th September 1799.

Church House, the colour-washed building by the northern entrance to St Mary’s churchyard, connects with the church, the oldest extant building in Calne. A blue plaque to Jan Ingen Housz, an early proponent of immunization and discoverer of photosynthesis, adorns its west side.

The building was renewed in 1581 when it was cited as a place where court meetings were held. It subsequently became known as the Guildhall and Church House. It was where the business and administration of the town took place. At the nearby proclamation steps, decisions, and enactments, as well as news items and events, were proclaimed, or shouted, at the people gathered there.

The burgesses, who maintained Church House, were responsible for borough administration, including the revenue from its lands and markets. Membership of the burgesses was restricted, typically around 17 or 18.

Church House was the town’s guildhall until the early 19th century when the administration moved to a house on Market Hill. In 1824 £52 was “given for repairs of Church House and Guildhall”. In 1829 the existing Town Hall on Market Hill was also used to serve as the new Guildhall. It was resolved that Church House, “be abandoned, and that the market house now handsomely fitted up by the marquis of Lansdowne be in future called the Guildhall.”

The Town Hall on Market Hill was demolished in 1882 when the decision was made to build a new town hall which still stands on the site of the old town mill.

• Jan Ingen Housz text: Nick Baxter
• Jan Ingen Housz audio: Nick Baxter
• About Church House text: Nick Baxter
• About Church House audio: Nick Baxter
• Building and Blue Plaque Images: Tim Havenith