That Sebastien Erard was the first of the new harp makers in London is undeniable. Not only was his company the nexus for the harp-buying public, it was from there that many second-, third- and forth-generation makers would come. Apprenticeship, despite being in decline as a mode of training, was at the heart of harp making, and Erard indentured future harp makers in the fields of wood-working, mechanics and finishing; however, he also employed cabinetmakers, and clock- and clock-case makers. Movement between makers was common. The following family tree, a preview taken from my forthcoming book, 'Harp Making in Late-Georgian England', shows these relationships and indentifies four first-generation makers; namely Erard, Erat, Dodd and Stumpff from whom the others originated. Inevitably there are missing links here; hopefully more evidence will come to light to identify these. The various sources are long and convoluted, particularly those that trace dates and addresses, so I won't go into those here. I hope that this, together with the text from the book, will help to date instruments and to estimate how many each maker made. Do feel free to comment. I'd be interested to know if I missed any of the larger makers; there is a section on minor makers in the book which I hope will be available soon after the world veneers itself with a semblance of normality.
Information about 'Harp Making in Late-Georgian England' can be found here - http://www.mike-baldwin.net