Portpatrick had long been a port for shipping between Scotland and Donaghadee in the north of Ireland, since at least 1620.

[1] During the construction of the Ayr and Maybole Junction line, a "Committee of Noblemen and Gentlemen" led by Sir James Fergusson of Kilkerran decided to form a company for the purpose of building a railway from Maybole to Girvan, and improving the jetty and harbour there.

[1] The main line finally opened for traffic on 24 May 1860,[4][5][6] although the harbour branch, an extension beyond the passenger terminus, a second bridge over the Water of Girvan, and the jetty were not ready at this stage.

[note 1] Notwithstanding the apparent desire to reach Portpatrick, the station was not laid out to enable onward running southwards.

The G&SWR was asked to finance the work, which it did, deducting the advance from the surplus on operations.

An underperforming local line worked by a larger sponsoring company could only end with absorption, and by the terms of the Glasgow and South-western Railway (Amalgamations) Act 1865 of 5 July 1865, the Maybole and Girvan Railway was absorbed by the larger company.

on 5 July 1865 to build from Girvan to Challoch Junction on the Portpatrick Railway, some distance east of Stranraer.

The finances of the new company were shaky and relations with existing railways were difficult, but in time matters settled down.

DMUs started operating over the line between Glasgow and Stranraer in 1959, with the current class 156 sprinters commencing in October 1988.

The line runs in a general south-westerly direction from Maybole through farmed countryside to Girvan, a fishing port on the Irish Sea.

[8][12] There was a rail connection to sidings in the depot, served from the Maidens and Dunure line.

A two-platform halt was erected at Grangeston, and two workers' trains ran to it from Ayr each morning.