In the course of researching ‘slave codes’ in the British empire, I came across mention of a five volume set named ‘Parliamentary Documents on Slavery and the Slave Trade.’ It was digitized by the University of Georgia, U.S.A., sometime around 2007, and is a collection of reports printed by the Parliament of Great Britain between 1788 and 1793.
Unfortunately, all links to it were dead, and Google only returned secondary references, not the books themselves. However, the Internet Archive’s Wayback Machine had mirrored the site, and a bit of digging led me to the complete series.