Ah, de Havilland in the 1950s, Mick!
I seem to remember word had got about that the stall tests were to be avoided - but they still used apprentoid mass as it could move itself for different CG positions, unlike the lead blocks (but the lead wasn't airsick).
I'm told by ex-Vickers folk that Vanguard power-on/power off stall tests were the worst flights in the industry.
(DHApprentice 1956-61)