The Duns Branch and the Berwickshire Railway together formed a through railway route from Reston, near Berwick-upon-Tweed, to St Boswells in the Scottish Borders. The line was promoted in two stages. The first was from Reston on the Edinburgh to Berwick main line to Duns (then spelt Dunse, and the county town of Berwickshire); it opened by the North British Railway in 1849. The North British Railway had conceived the line as a strategic trunk route across southern Scotland, but this development was never realised, and the line was never heavily used.