|Founder||Owen Philipps, 1st Baron Kylsant|
|England, Ireland, Wales, Scotland, Channel Islands|
Powell, Bacon and Hough Lines Ltd was formed in 1913 in Liverpool. The name of Coast Lines Limited was adopted in 1917, when the company was purchased by the Royal Mail Steam Packet Company at a cost of £800,000. (equivalent to £44,034,615 in 2018),
In 1931, the Royal Mail Steam Packet Company was dissolved after the Royal Mail Case and the chairman Lord Kylsant was imprisoned in 1931 for misrepresenting the state of the company to shareholders. Coast Lines achieved independence under the chairmanship of Sir Alfred Read (1871-1955), who had previously been a director.
From 1917 to 1951, Coast Lines acquired a controlling interest in a large number of coastal shipping companies, eventually numbering about twenty, of which the most important were:
- British and Irish Steam Packet Company (1917)
- City of Cork Steam Packet Company (1918)
- Laird Lines (1919)
- Belfast Steamship Company (1919)
- Tedcastle McCormick and Company (1919)
- City of Dublin Steam Packet Company (1919)
- Ayr Steam Shipping Company (1919)
- G & J Burns Ltd (1920)
- Burns Steamship Company (1920)
- Ardrossan Harbour Company (1920)
- Little Western Steamship Company (1920)
- London Welsh Steamship Company (1924)
- British Motor Ship Company (1925)
- John Westcott Ltd (1925)
- Dundalk and Newry Steam Packet Company (1926)
- Michael Murphy Limited (1926)
- David MacBrayne Ltd (jointly with the London, Midland and Scottish Railway) (1928)
- Tyne Tees Steam Shipping Company (1943)
- North of Scotland, Orkney & Shetland Steam Navigation Company (1961)
By 1951, the company operated a fleet of 109 ships, which carried over four million tons of cargo, over half a million head of livestock, and more than a million passengers.
The remains of the company was acquired by P&O Ferries in 1971
- Sea breezes: the ship lovers' digest: 1949
- A business of national importance: the Royal Mail Shipping Group, 1902-1937 By Edwin Green, Michael S. Moss
- UK Retail Price Index inflation figures are based on data from Clark, Gregory (2017). "The Annual RPI and Average Earnings for Britain, 1209 to Present (New Series)". MeasuringWorth. Retrieved 27 January 2019.
- Shipping Lines: Royal Mail Steam Packet Company
- 'The world's largest coaster fleet', Sea Breezes, E.R. Reader, February 1949.
- Robins, Nick; MacRonald, Malcolm (2017). Powell, Bacon and Hough: Formation of Coast Lines Limited. Portishead, Bristol: Coastal Shipping Publications. ISBN 9781902953816.