The company was formed out of Messrs. Middleton and Pollexfen a trading partnership based in Sligo.

In 1936 Coast Lines Ltd bought Sligo Steamship Navigation Company.

The company offices were based in Wine street in the town.

The SS Liverpool, the biggest vessel operated by the company, was built by Messrs John Jones & Sons and was 686 gross tons.

[1] The steamship SS Liverpool was lost off the south coast of the Isle of Man on 16 December 1916, after hitting a mine laid by a German submarine.