Among the principal beneficiaries of this booming trade were John Campbell (Senior) and Company, which supplied merchandise to the slave plantations along the coast of Guiana, then in Dutch hands. It was in this role of supplier that the company first began to acquire plantations along the Essequibo Coast of Guiana, from planters facing bankruptcy. By the 20th century, the company of Curtis, Campbell and Co had its established place in the British Guiana plantocracy; When Jock's great-grandfather, Colin Campbell of Colgrain, died in 1886 he left £627,000. When his grandfather, William Middleton Campbell died in 1919, he left £711,000.