Great graphics Discorde!!
D P Davies ( aka HTBJs ) in his radio talks makes mention of an "along wing airflow" on four engined prop aircraft which invariably leads to some nasty stalling characteristics, hence the admonishment with the Vanguard to "not progress the stall beyond the initial buffet". Ron Gillman in his excellent book Croydon to Concord describes such an incident and probably explains why the subject airframe never seemed to fly "true" afterwards.