Pension schemes, when they were inaugurated, usually promised a level of retirement benefits in an apparently firm formula, which was felt, at the time, to suit the needs of employer and members alike. When retirement came – forty years later for young members of newly inaugurated schemes – it was rare for the original benefit structure to have been retained. The twentieth-century experience so far thus suggests that pension promises are not firm, but are subject to quite frequent alteration. As we saw in the previous chapter, alterations are subject to certain legal safeguards, but are principally determined by the needs of the employment contract and the financial well-being of the fund. These factors might be expected to produce a rich variety in pension benefit formulae, and in the past they have done so. More recently, however, there has been a remarkable convergence of pension schemes on what appears to be a standard design.