My late father was OC Standards Flight at Heany from late 52 to 53. He subsequently went to Moreton (Much Binding) in the Marsh and flew the last Harvard out on the 28th Feb 1955 when it closed.
According to him the Harvard had one particular vice. With two up the student in the front would get used to the elevator trim position. When solo he would find that he was having to hold back the control column because of the differing C of G. Naturally winding on more nose up to relieve this would bring the trim almost to its limit. Should he screw up the three pointer landing and start to lose it opening the throttle wide to over shoot could be fatal. The aircraft would pitch up, stall, turn over and smash into the runway upside down.
The Balliol had a similar vice; though torque induced from the Merlin.
Pilots were cheap in those days.