H. N. Irving & Son was one of the last firms of bespoke telescope makers. Based at 258 Kingston Road for most of the 20th century, Horace N. and Ronald N. Irving established a reputation for excellent craftsmanship; Patrick Moore was a regular visitor as a young boy. Ron Irving joined the company in 1936 and became sole proprietor on the death of his father in 1941. He died in 2005. Irving & Son mainly made Newtonian reflecting telescopes, later providing parts and accessories as Ron Irving's health declined and made it difficult to build large instruments. He was also involved in restoring antique telescopes, notable the 10-inch Calver at Brayebrook Observatory. To supplement the telescope making business Ron Irving also took on work for the National Physical laboratory, designing hypsometer test baths to calibrate high-pressure thermometers. These were sold worldwide: the correspondence indicates that items went as far afield as South Africa and India.