BAe might not be much of a company when it comes to designing aircraft - but they have been superbly successful in extracting money from the MOD across a huge variety of 'issues'.
Things like the in excess of £1M Nimrod safety case - which was not wortht he paper it was written on come to mind.
A set of inspection hatches and routine ndt is going to be far far more effective at spotting fatigue than a calculated fatigue life which features all sorts of global modifiers to try and account for manufacturing tolerances and differences in use.
In my day job we routinely deal with structures which have negative fatigue lives, for steel the research suggests actual fatigue lives typcially vary from the calculated life to in excess of 20 times the calculated life - with failure at calculate life being exceptional.........
So a great deal of potential for a structured review of real life performance and the methodology that BAe used to arrive at their fatigue index.