What I forgot to mention was that the late Lord Pym MC PC DL's statement was set against a 5.02% of GDP Defence budget (not including pensions). AFPS expenditure, I believe, accounts for c.3% of the current defence budget.
There is of course also the anomaly between what MOD says the budget is and the bigger amount reported to NATO as defence related expenditure (CSSF, JSF, civilian pensions etc.).