The fit between law and insurance was a natural one. In 1836, of the fifteen directors of the Standard Life Assurance Company in Edinburgh, six were writers to the signet and one, George Patton, was an advocate. The manager, James Cheyne WS, was also a lawyer. Albeit at a less exalted level, our knowledge of Craig's work as an insurance agent comes mainly from the correspondence which he and Elliot Anderson had with the Edinburgh accountant Henry David Dickie (1792–1863), secretary of the Caledonian Insurance Company. Despite becoming manager of the company in 1828, Dickie remained the main correspondent for Craig until the appointment of John Moinet in 1835 as company secretary.

Insurance, like banking, required local knowledge, if risks were to be properly assessed, and Craig was much in demand for his services. In 1806, he had been one of the first agents appointed by what was then the Caledonian Fire Office (established in Edinburgh in 1805 and later describing itself as ‘the oldest Scottish establishment but one’). That, together with his later employment by the London Union Assurance Company, obliged him to turn down an approach to act as agent for the Scottish Union Insurance Company. He also refused an offer from Sir John Hope to become local agent for both the fire and life departments of the Guardian Assurance Company in Edinburgh.

Craig was more at home in banking than insurance. Neither he nor Anderson can be described as insurance experts, although they expanded their knowledge and made efforts to understand the practice of head office, sending queries whenever clarification was required. Insurance was still a developing industry and the terms of policies were being adjusted as understanding grew about the quantum of risk. Craig's practice was to write out the details of each policy in a memorandum book which apparently no longer survives.