This extensive and remarkably complete series covers the whole range of the business activities of the firm with some mention of the family's private affairs and of the Pitfour estate. There are letters to tack holders, to individual fisherman, coopers, shipmasters, merchants and financiers, bakers and painters, providing a very detailed picture of the day to day running of the business.

Although in the main these are general letter books, MS.20808 concerns the purchase of wheat and flour milling, and MSS.20820, 20824, 20828, and 20832 chiefly concern the Tay fishing concern.