The legal firm of Mitchells, Johnston & Co , founded by Thomas Grahame in c1745 , and were appointed the University of Glasgow's law agents in 1776 . In the 1830s the company became deeply involved with railway work. This was a major concern of James Mitchell and, later, his cousin and partner, Alexander Oswald Mitchell. The firm was involved with many of the early Scottish railway lines subsequently absorbed by the Caledonian Railway or the North British Railway Co , and in acting as agents for these companies, amassed a large collection of papers relating to railway cases.
From the guide to the Records of Mitchells, Johnston & Co, solicitors, Glasgow, Scotland, 1824-1969, (Glasgow University Archive Services)