On his return journey from Sydney in March and April 1958, Utzon stopped off to visit China, Japan and Nepal, despite the enormous amount of work to be done on the podium. This was the first of a series of absences by Utzon at critical junctures in the programme. Later, when he moved to Australia, he closed his office down for three months and went travelling. Arups were unable to contact him and were forced to make a number of design decisions without Utzon's input. This was to have a significant effect on Utzon's relationship with his engineers.
However, in 1958 Ove Arup was still able to treat such incidents light-heartedly. When Utzon returned to Hellebaek, he wrote, 'It was nice to hear from you. I really thought you were lost in the wilds of Asia.'
For the next four years, the two men-and their teams-enjoyed a collaboration that was remarkable in its fruitfulness and, despite many traumas, was seen by most of those involved as a high point of architect/engineer collaboration.
The partner responsible for the project was Ronald Jenkins, although Arup, because of his Danish connections, was closely involved in the development of the designs.
Jenkins-whose initials, felicitously for an engineer, were RSJ-was a brilliant mathematician. Shy and socially diffident, he provided the hard detail that supported Arup's broadbrush philosophical approach. When Arup set up his firm of consulting engineers in 1946, Jenkins joined him becoming a senior partner in 1949. His major projects prior to the Opera House were the Brynmawr Rubber Company Factory, Hunstanton School-the seminal brutalist building by Alison and Peter Smithson-and a timber, hyperbolic paraboloid roof at Market Drayton. Peter Rice described him as 'an engineer whose mathematical