On Open Big Data, our directory of open access datasets for social science research, we have published a master dataset of historical advertisements of The Economist now.
This FAIR dataset contains metadata of 512.599 historical advertisements from all 8,840 issues of The Economist magazine, years 1843 to 2014. It is part of a series of datasets related to The Economist Historical Archive.
Check this out if you are looking for historical data on advertisements for your research: http://openbigdata.directory/