AbstractMoving from Operational Research to Corporate Planning within one organisation is a rather modest change, which nevertheless leads to a different perspective. While still an advisory function, Corporate Planning, to be successful, has to maintain itself at the centre of a `messy' system tackling `messy' problems. Holding on to a clear strategy in such circumstances is not only difficult but vital. The success of the strategy depends on its robustness and ability to adapt to new circumstances. Recent debates in the O.R. literature have focused on the importance of robustness and the nature of uncertainty using the paradigms of rational and bureaucratic processes. This is a useful perspective from which to view our activities and the relative roles of Operational Research and Corporate Planning, either separately or together. The term `mature' O.R. is used to differentiate research that has been built up over many years in the N.C.B. from the problem solving activity often used to characterise O.R. The challenge is to prevent maturity developing into old age.