According to the letters, Bolton imports cloth and grain from England; and furniture, clothes, leather, glass, and small manufactures. He exports to England and America wine and brandy and sugar-preserved fruit. He passes on to other markets goods Heysham has sent him that do not sell in Madeira; and he deals in Barbados sugar.

Bolton reports the merchant and military ships that call at or pass Madeira: their origin, destination, cargo, name, type, and captain; and news from the West Indies of shipping lost and battles. He orders specific quantities and types of cloth and specific items, and complains when shipments are rotten or will not sell.

Bolton additionally reports the state of the vintage, the quality and quantity of the wines, the market and probable price, the state of the weather and of the harvest, and the market for grain (undercut in later years by shipments from America). He lists bills forwarded and names the bankers they are drawn on and discusses insurance. He says little about the native Madeiran population or politics, although he is exiled temporarily in 1696 and must plead his case in Lisbon, Portugal. He makes provision for his relatives in England.

These seem to be letters received by Heysham and not retained copies; a few still have address and seal. Many hands appear, presumably those of clerks. Bolton signs himself "William Bolton" when he is writing on his "own account"; sometimes the letters refer to "our W.B." The first letter is written from Plymouth in 1695, giving plans for his Company; the rest are from Madeira or Lisbon. Bolton himself seems to return permanently to England in 1703.

There are additionally four items in the collection that are not letters from Bolton to a Heysham brother; these items are at the end of the collection.