As an instrument tech at BZN I was involved in recalibrating the stall warning systems speeds on the Belfast, in order to increase the margin between the warning and the actual stall. A Belfast had encountered ice over the Alps along with tail de-icing failure and the stall warning system had not operated as required with the aircraft at a high nose-up angle. We did the adjustments by trial and error, with the crew holding the nose until the actual stall occurred for each tweak of the setting until we got the target margin of [30 knots?]. We covered all flap settings and I recall that the aircraft lost some 5.000 feet in the "clean" stall condition - producing some interesting comments during the first try, as we wondered if it ever would recover!
For civil certification the CAA predictably insisted on having a stick pusher installed.