"The underlying 'assumptions' are (1) a uniform income yield; (2) a uniform rate of capital growth; (3) a uniform rate of inflation; (4) a consistent regime of taxation - with bands/allowances increasing in line with inflation; (5) a constant level of drawdown in real terms; (6) a consistent rate of 'churn' (the realisation of capital gains other than to fund expenditure); and that the recipient will (7) survive for precisely the expected average of her (or occasionally his) contemporaries; and (8) be or become entitled to a 'full' state pension; which will (9) increase in line with prices; while (10) the age at which a state pension is payable will not alter in the meantime. All of the assumptions are necessary simplifications which will not materialise: as Ward LJ said in B v B[1990] 1 FLR 20 'the only certainty is that it will not happen as we have predicted'. […] The assumptions include three key financial predictions - an average income yield of 3% p.a., an average capital growth of 3.75% p.a. and average inflation of 3% p.a."
"In summary, it is not wise to assume that because the Duxbury Committee are of the opinion that in the context of their calculations 3.75% gross is achievable over the long term with a cautious investment strategy that the parties will agree that that rate is applicable to capital funds that are not to be amortised on the facts of a particular case. However, if they do agree or if the judge decides that assumption is valid on the facts of a case, I cannot for my part see how objection can be taken. If they do not, then the rate chosen by the court should be reasoned."