Series MS 105/6/1 - Papers from deed box marked "Forth Bridge and Tay Bridge Papers".

The North British Railway Company was incorporated in 1844, gaining authorisation to operate a line running from Berwick to Edinburgh with a four mile long branch line running to Haddington. The main line opened in 1846 with the branch line operating from 1856. The North British soon expanded its influence both by absorbing rival railway companies (for example the Edinburgh and Glasgow line was taken over in 1865), and by becoming involved in large building projects such as the building of the Tay rail bridge in 1878 and, in a joint venture with the Midland and the Great Northern and North Eastern companies, the building of the Forth rail bridge in 1881. The North British Railway Company was absorbed into the London and North Eastern Railway Company in 1923.