Communities in rural areas found that a railway connection reduced the cost of necessities considerably, and made it cheaper to get local manufactures to market.

The area around Penicuik itself was found to be rich in minerals, and the Shotts Iron Company established extensive ironstone and coal pits in the locality.

The line primarily served paper mills adjacent to the river, and because of the terrain was unsuitable for connecting to the pits.

[1][2][5][6][7][8] The Board of Trade Inspecting Officer visited the line on 12 and 19 January 1872 to consider approval for passenger train operation.

[1][8] Although it was the mineral working around Penicuik which had prompted the idea of the line, in fact it served paper mills primarily; they required copious supplies of water and were located in the valley floor.

It was the ELRR, running at a higher level on the west side of the River Esk, which actually connected into the mineral workings.

[1] In 1875, the Shotts Iron Company sank a new shaft at Greenlaw near Glencorse Barracks, and (encouraged by the NBR) the ELRR sought parliamentary authority to extend the line to serve the mine.

[4][5] The North British Railway promised that they would "in all time coming keep up as efficient a passenger train service as at present".

[1][4] The line served several paper mills, and the attractive nature of the area encouraged residential travel by Edinburgh professionals.

The cost of the rectification considerably exceeded income, and the line was closed to all traffic on 27 March 1967,[7][8][13] and the tracks were quickly lifted.