Anthropological Institute
Auction Mart near Bank of England
Mr Bolton, Cockermouth
Last, Shrewsbury
Royal United Services Institution Museum
Sothebys
Williamson
Bryce Wright
As can be seen he mostly purchased the English items from institutes which were closing their museums (Anthropological and Royal United Services Institutes), from professional dealers like Bryce Wright, auction houses like Sothebys and the unnamed Auction Mart, and from individuals such as Mr Bolton and possibly Williamson. It is not clear whether Last is either a local auction firm or a dealer.
To find out more about Pitt Rivers and his collections go to here.