In the First World War the Royal Mail Steam Packet Company lost a number of ships to enemy action, including three of its "A-series" passenger liners: Alcantara, Aragon and Asturias.

[12] Each of the two new ships was powered by a pair of eight-cylinder four-stroke double-acting diesel engines built by Harland and Wolff to a Burmeister & Wain design.

[13] In comparison, Compagnie de Navigation Sud-Atlantique had two 15,000 GRT liners on the route, Lutetia (1913) and Massilia (1920), that were smaller and older but at 20 knots (37 km/h)[14] could offer a passage that was quicker by several days.

He claimed that German, Italian, and French competitors were running ships to South America at 22 knots (41 km/h), giving a passage about five days quicker than RMSP.

Essendon also proposed inviting foreign competitors to agree on a 19-knot speed limit on the South American route, so that all companies could economise on fuel and attempt to cover their costs.

[18] At that time marine diesel power was at a relatively early stage of development, and RML considered it unable to increase the two ships' speed to the required level.

Lord Essendon therefore recommended steam turbines, and two options for the drive system: either conventional reduction gearing, or the newer turbo-electric transmission that had been pioneered in the USA and successfully applied to US, UK and French ocean liners.

RML awarded the work to Harland and Wolff, but with a condition in the contract that the ships must achieve at least 18+3⁄4 knots (34.7 km/h), and a graduated penalty clause in case the actual speed increase should fall short of that figure.

[15] Harland and Wolff fitted each ship with three water-tube boilers supplying superheated steam at 435 lbf/in2 to a set of six turbines that drove her twin propeller shafts by single reduction gearing.

Only after Asturias had successfully completed a voyage from Southampton to Rio de Janeiro and back did RMSP send Alcantara to Harland and Wolff at Belfast in November.

Asturias remained in UK Government service as an emigrant ship, and Alcantara resumed their route between Southampton and South America, together with Andes.

Eventually, the panels were not reused but were sold to the Parish Church of Our Lady of Graces in Żabbar, Malta, where they were used as the platform for the 1951 titular painting coronation ceremony.