The Whithorn extension was ready for a ceremonial opening on 7 July 1877 and it was opened to the public on 9 July; a fifth engine, another 2-2-2 well tank, was obtained by Wheatley; formerly no. 31A of the NBR, it became WR no. 5. The Garliestown section was now operated as a shuttle branch line from a new Millisle station, 7 chains (140 m) north of the original Garliestown station. In December 1877 a platform was provided at Broughton Skeog level crossing. There were four passenger (or mixed) trains each way daily on the Whithorn main line, and seven shuttle services on the Garliestown branch. As well as passengers, cattle were a dominant traffic from the agricultural activity in the area, and imports from the harbours also. Excursion steamers ran from Garliestown to the Isle of Man, and excursion trains ran in connection from Stranraer and Dumfries.