Hi Derek
The City of Durban was of course the last of the four City of Port Elizabeth class to be built by Vickers at Walker Naval Yard on the Tyne. They normally disembarked passengers, hotel staff and some cargo at London and then worked their way up the North Sea to Newcastle, before returning to London to pick up outward bound passengers. Not the best way to maximise the return on Ellerman's investment in their passenger accommodation, but life was more relaxed in those days.
I remember watching them pass my office window in the 1960's when I worked at Hawthorn Leslie (Engineers) Ltd at St Peters, which was just down river from their Newcastle berth. Hawthorn Leslie built all eight Doxford diesel engines for the ships and we had a service contract from Ellerman. A spare cylinder liner and its gear was provided. Every time one of the ships arrived at Newcastle our engineers would go on-board and remove and replace a cylinder liner on a rotation basis. The old cylinder liner was taken back to St Peters and refurbished in time to repeat the process on the arrival of the next ship in the class. An early form of preventative maintenance in action.