I remember this accident well since I had recently finished flying training at the College of Air Training Hamble when it occured. The two copilots on board had been Hamble trained and sadly lost their lives along with everyone else.
I recall that as a direct result of this accident the CAA (Ministry of Aviation then) made incapacitation training a mandatory element on pilot proficiency checks. In other words you were given training in how to detect subtle incapacitation of a fellow crew member and what to do should this event occur.
This was also before the days of Mandatory Occurence Reporting (MOR) and BEA had had at least one very close accident when the droop had been retracted at too low a speed. This incident was reported internally but no action had been taken. I seem to remember that this was also the catalyst that brought in the MOR system etc.
This was also before the days of Cockpit Resource Management training and one would like to think that this type of accident would be impossible now. It was a tragic accident and many lessons were learned from it.