One must assume the AIA deal is a board decision not just that of the CEO at the Pru and that the financial department within the Pru are doing all the real donkey work in the mechanics of the financial models for the propectus. That not to say Thiam should not intimately be involved as he has to sell the deal to investors but its never a one man show.
Equally I think it is a good idea that he has a couple of non executive roles as you say it broadens his experiance and puts him in contact with a wider network. You get the sense with UK institutional investors that they want a "football manager" rather than a well rounded businessman.
