The first commercial vessel to be driven by steam turbines, King Edward operated as a Clyde steamer for half a century from 1901 until 1951, interrupted only by service in the two world wars.

In 1803, Charlotte Dundas showed the practicality of steam power for marine use, and in 1812 Henry Bell's PS Comet began the first commercially successful steamboat service in Europe, sailing on the River Clyde between Glasgow and Helensburgh.

[6] In a famous publicity stunt, Parson's steam launch sped uninvited past warships in the Solent at the 1897 Review of the Fleet held on the Diamond Jubilee of Queen Victoria's accession to the throne.

Its manufacturing and operating characteristics were widely known; it had attained a high degree of fuel efficiency, and functioned economically across a range of speeds.

These included the PS Strathmore, built to order in 1897, which took over the service running from Fairlie Pier railway station to Campbeltown, and proved reliable.

Towards the end of 1900 a syndicate was formed in which he agreed to personally operate the proposed ship for its first season without pay, William Denny and Brothers would build the hull and boilers, and the Parsons Marine Steam Turbine Company was to provide the machinery.

prohibited its own vessels from serving:[13] Fairlie and Campbeltown Steamboat Service – Captain John Williamson, having represented that he had arranged with others for the building of a steamer with Parsons turbine engines and Propellors–It was agreed to guarantee his overdraft with the National Bank of Scotland conditionally on Captain Williamson placing and maintaining the Steamer on the Fairlie route next summer.

[13] The hull design of King Edward was closely based by Denny on its successful steamer, PS Duchess of Hamilton, and shared the main dimensions.

[20] The power plant consisted of Scotch marine boilers providing steam at 150 pounds per square inch (1,000 kPa) to Parsons turbines.

The propulsion system differed from that of the lightly built destroyers, which operated under higher steam pressure and drove four propeller shafts.

[23] The builders had tested the hull form in their own tank, and hoped to attain a speed of 20 knots (37 km/h; 23 mph) with the turbine machinery.

After full hull cleaning at Scott's of Greenock a further series of trials took place on 24 June: in seven return runs over the mile, the best mean speed attained was 19.7 knots (36.5 km/h; 22.7 mph).

At the official trial on 28 June, invited guests came aboard off Craigendoran, and the ship then sailed to Campbeltown with intermediate visits to Dunoon, Rothesay, Largs, Fairlie and Lochranza, where Duchess of Hamilton waited with a special party of members of the Institute of Naval Architects.

King Edward's performance was compared with that of Duchess of Hamilton, the similar vessel built by Denny at about the same time, but with reciprocating machinery driving paddle wheels.

[24] King Edward entered service on 1 July 1901, with a daily sailing leaving the Glasgow and South Western Railway's Prince's Pier, Greenock, at an advertised time of 8.40 a.m., visiting Dunoon and Rothesay before calling at the G&SWR's Fairlie Pier railway station at 10.20 a.m. then sailing across the Firth to Lochranza and on to arrive at Campbeltown at 12.20.

For a small additional cost, horse-drawn coach trips from Campbeltown to Machrihanish offered a "Daily Excursion to the Shores of the Atlantic".

The G&SWR also offered an Isle of Arran tour, taking PS Juno from Prince's Pier via the Kyles of Bute to Brodick, then travelling by coach to Lochranza to catch King Edward for the return voyage, or a similar arrangement in reverse order.

[29] The route was changed so that instead of going via Fairlie and Garroch Head, the ship went through the Kyles of Bute and gave direct competition to the other steamers on the run.

By 1912 the battle was over, and Lord of the Isles (together with the paddler Edinburgh Castle which was also owned by an amalgamation of the Inveraray and Loch Goil companies) was taken over by Turbine Steamers Ltd.[28] During the Great War, King Edward ferried troops across the English Channel.

[21][30] A merger of shipowners in 1919 had formed Williamson-Buchanan Steamers Ltd. which still traded as John Williamson and Company and retained as standard white funnels with black tops.

[31] In World War II King Edward ran for a time on the peacetime route, then became a tender for troopships arriving at the Clyde.

[22] This success led almost immediately to orders for several other turbine Clyde steamers, and other vessels for short-sea trades across the Irish Sea and English Channel.