My first cycle trip to Southend was a week or so after Viscount G-AVJZ had crashed. At that time G-AIKN was clealy visible from the spectator terrace dumped near the compass circle at the far end of 33/15. G-APOP was on the far side of the airport either inside or outside the old Tradair hangar and G-APOO may have been there with it along with several Channel Airways Dakotas.
According to my ancient copy of BCAR G-AHPE was scrapped at Gatwick in June 61 so that was probably the one on the fire dump and G-AJBX was withdrawn from use at Manston in May 1965.
BCAR shows G-APOP as withdrawn from use in Jan 1965 but it wasn’t broken up until 5 years later in January 1970. I remember that the Southend museum didn’t consider any of the Channel Airways Dakotas or the Viking as being viable for preservation because they were missing a lot of bits and had the wings off. In those days the resources simply weren’t available to tackle anything which wasn’t already substantially complete. The preservation movement has come a long way since then.