TM, This Trident accident was a harsh lesson for the design / regulatory process, and was a basis for modern standards for stall warning and avoidance.
This should not be confused with the ‘Staines’ Trident accident which was associated with Human interaction.
It would be misleading to associate the Trident stall with AF447. The differences are that the Trident involved a ‘locked in’ deep stall, where there were no further control resources available to recover, whereas AF447 may have involved a deep stall (depending on definition), it was not ‘locked in’ because some form of control remained for recovery. i.e. the difference between physically not being able to recover, vs having capability but not using it, or recognising the need to use it.