Lake Como was part of the Grand Tour and the scientific skills of local instrument makers were communicated in writings of travellers to the region. During the last quarter of the eighteen century numbers of them began to leave their towns and villages and came to London. These early migrants included carvers, gilders, and glassblowers.
While the scientific observation of atmospheric pressure lay behind their craft, economic and political pressure forced their departure. Lombardy at the time was ruthlessly exploited by the ruling Habsburgs. By the end of the century conditions further deteriorated when the French invaded the province and introduced conscription. The first Italian instrument makers scattered across a few streets to the north of Holborn which was an area of skilled craftsmen including clock and watch makers, umbrella makers, etc.
They lived and worked closely together, often in partnerships; they intermarried and family members moved out to Liverpool, Manchester, and as far as New York. Giovanni Maria Ronchetti [John Merry Ronketto] arrived in London around 1780 and established his firm at no. 180 Holborn; Joseph Somalvico settled in Holborn around 1780; James Garry (his Italian name is not known) started work at no. 132 High Holborn during the 1780s; Domenico [Dominick] Manticha was recorded as working from Ely Court, Holborn, between 1789 and 1805; D. Martinelli was producing barometers in 1799 out of no. 82 Leather Lane; in 1803 Francis Anone ran a workshop at no. 26 High Holborn;
Domenico [Domenick] Lione settled at no. 125 Holborn Hill where he worked between 1805 and 1819; Della Torre ran his firm in partnership with Giovanni [John] Barelli from no. 9 Lamb’s Conduit Street from 1826. Some of these firms were carried on for generations, the biggest name being that of Negretti & Zambra who were in business from the mid-nineteenth century until being taken over in 1981.