The Union-Castle/Safmarine joint mailship service declined heavily during the 1970s. This was due to a combination of adverse economic factors including the loss of earnings from high value cargoes, which were increasingly being carried in the more efficient, revolutionary new container ships. With the large increase in oil prices in 1973, the mail ship schedule was extended by one day to allow more economical steaming. After "Pendennis Castle" was withdrawn in June 1976 just two mailships remained on the route – Union-Castle's "Windsor Castle" and Safmarine's "S.A. Vaal" – in addition to Union-Castle's last cargo/passenger vessels RMMV "Good Hope Castle" and RMMV "Southampton Castle" (carrying just 12 passengers each) and other chartered cargo-only tonnage. The jointly owned passenger liner service ceased completely in October 1977, with the "S.A. Vaal" being the last to arrive in Southampton on 10 October 1977.