Industrial disputes at Harland and Wolff delayed the construction of Pendennis Castle, culminating in the vessel being launched without ceremony on Christmas Eve 1957, 14 days after her naming and blessing.

Windsor Castle - the only Union-Castle ship ordered from Cammell Laird - was also briefly the largest liner built in England, until surpassed by the 41,910 GRT Orient Line's Oriana launched on 3 November 1959.

After sea-trials and a brief delivery sailing with Union-Castle office staff acting as passengers, Windsor Castle's commercial maiden voyage was from Southampton to Durban on 18 August 1960.

Windsor Castle was now required (like her fleetmates) to sail at her designed 221⁄2 knots and the time honoured Thursday at 4 o'clock departure became Friday at 1 o'clock By the mid-1970s the operation of Windsor Castle and her Union-Castle/Safmarine mailship consorts had become unprofitable due to a combination of factors: the introduction of the 'Jumbo Jet' which moved large numbers quickly and economically; further from the fading attraction for new settlers of the increasingly politically isolated South Africa of the time; also challenging the labour-intensive conventional cargo facilities in the mailships were the hugely successful new container ships which enabled cargoes to be moved faster and more efficiently.

[1] The vessel was promptly sold to Yiannis Latsis the Greek finance and shipping magnate, charity patron and benefactor, and renamed Margarita L, in honour of his daughter.

After a refit in Piraeus Margarita L was despatched to Jeddah, Saudi Arabia, for use as an office, leisure centre and static accommodation facility for one of Latsis's companies, Petrola International SA.

In the absence of any other substantive offers, Latsis Lines sold Margarita L in December 2004 to an undisclosed party, with the view to disposing of the vessel to Indian scrap merchants.

After some months were spent reactivating long idle main engines, the vessel sailed to India for the breakers on 14 April 2005, under the shortened name Rita, despite a number of attempts to save her.

Having arrived off Alang, Rita was turned back to United Arab Emirates waters, while the interim owners apparently awaited an improvement in the value of scrap steel.