RMS Strathaird, later TSS Strathaird, was an ocean liner of the Peninsular and Oriental Steam Navigation Company (P&O). She was the second of five sister ships in what came to be called the "Strath" class. All previous P&O steamships had black-painted hulls and funnels but Strathaird and her sisters were painted with white hulls and buff funnels, which earned them the nickname "The Beautiful White Sisters" or just "The White Sisters". Strathaird and her sister ship were Royal Mail Ships that worked P&O's regular liner route between Tilbury in Essex, England and Brisbane in Queensland, Australia. In 1935, they were joined by the third ship of the class, . Strathaird remained in service for almost 30 years, being scrapped in 1961. Building The Vickers-Armstrong shipyard at Barrow-in-Furness built all five "Strath" class liners. Strathaird was launched on 18 July 1931, completed in January 1932, and left Tilbury on her maiden voyage on 12 February 1932. In 1929, P&O had introduced its first large turbo-electric liner, . The company chose the same propulsion system for Strathnaver and Strathaird, but the "Straths" were slightly larger ships, their turbo-electric equipment was much more powerful and they were about faster than Viceroy of India. Strathaird was very similar to Strathnaver. Each had four water-tube boilers and two auxiliary boilers. The boilers had a combined heating surface of and supplied steam at 425 lbf/in2 to two turbo generators. These supplied current to two electric motors with a combined rating of 6,315 NHP or 28,000 shp. British Thomson-Houston of Rugby, Warwickshire built the turbo-generators and motors. The motors drove a pair of inward-rotating screw propellers. Like Strathnaver, Strathaird had three funnels but only the middle one served as a smoke stack: the first and third funnels were dummies. Strathaird and Strathnaver were each equipped with direction finding equipment, an echo sounding device and a gyrocompass As built, Strathaird had accommodation for 498 first class and 668 tourist class passengers. Service Strathaird joined Strathnaver on the Tilbury — Brisbane route via the Suez Canal. However, in December 1932, Strathaird became the first P&O ship to work a cruise, when she took a five-day excursion from Sydney to Norfolk Island. Later in the 1930s, she made occasional cruises from UK ports. In 1939 or 1940, the two sisters were requisitioned as troop ships. Strathaird made two convoy voyages taking troops from Australasia to the Middle East Theatre of