Noble, politician and diplomat. Educated in Oxford, Campbell was styled Lord Glenorchy until he inherited the estates and titles of Breadalbane from his father, another John Campbell (1662 - 1752), who was known as Old Rag.
Campbell served as British Ambassador to Denmark (1720-30) and Russia (1731). He was also a politician, representing English constituencies (1727-46) and serving in Sir Robert Walpole's government in several capacities. He went on to serve as a Scottish Representative Peer (1752-68), Keeper of the Privy Seal (1765-66) and Vice-Admiral of Scotland (1776-82).