Taking up A10 Thundybox's mention of Typhoon's Operational Evaluation - one has to question the reasons why the taxpayer commits £18bn to an aircraft and accepts it before such an evaluation. Why is the acceptance not subject to that evaluation in the same way the C of A clearance is required before it enters service? Maybe if it was we would get weapons systems as well as airframes and engines.
I remember the Operational Evaluation of the F15 and the interested aircraft companies were crawling all over the USAF and pouring their own dollars into getting it through. Why do we trust BWoS so much?