I am currently working on a project on 18th-century trade directories and their role in providing direction as well as in restructuring urban space through practices such as house numbering. It appears likely that directories helped to establish standardized and more concise forms of addressing. However, it is not entirely clear whether the styles of address suggested in directories were indeed adopted by letter writers. Therefore I would like to look at samples of letters and envelopes of the late 17th through early 19th centuries to determine whether any changes in addressing can be observed.
Does anyone know any larger collections of letters in British archives that might be worth looking at?