Documentation
Wensleydale's post about documentation revived memories of the E-3D trial programme.
Apparently when the Boscombe Down team set about planning the E-3D trial programme it looked at the agreed contractual method of testing for the respective aircraft and mission systems.
Against some items it read "PV" meaning it had been previously verified and did not need to be tested. This had been agreed by the civil servants managing the project in the then MOD PE.
When the team asked for proof of how the systems had been tested the reply was that proof of verification was not part of the contract. I believe this led to a separate contract having to be set up for the documentation to be provided.