The North British Railway Co , Edinburgh, Scotland, was formed in 1844 and was the name chosen by the promoters of a proposed line from Edinburgh, Scotland, to Berwick-on-Tweed, England. The line opened in 1846 and provided a service between Berwick and Edinburgh with a branch between Longniddry and Haddington, East Lothian, Scotland. Later expansions and acquisitions provided lines to Glasgow, Stirling, Dundee, Hamilton, Peebles, Galashiels, Aberdeen, St Andrews in Scotland, and Carlisle, England. The company purchased the Edinburgh & Glasgow Railway Co in 1865 . Ultimately this company owned the largest track mileage of any Scottish railway company. It became part of the London & North East Railway in 1923 , stretching from London, England, to Lossiemouth, Scotland. The company was nationalised as part of British Rail in 1948.
From the guide to the Records of the North British Railway Co., Edinburgh, Scotland, 1844-1922, (Glasgow University Archive Services)