In my book, relatives knew that Sheila was staying at the farmhouse on evening 6th August 1985, and that on the following day, June intended to come and see Pamela about Sheila's behaviour which was described as having been very strange...
If Sheila's strange behaviour was linked to a recent meeting with the aforementioned cousin, and things were about to come to a head, it presented a five hour window of opportunity for the cousin to take the appropriate action, to get rid of her and the rest of the family, and to pin the blame onto Jeremy, but if true, it makes you wonder whether or not, the cousin fooled Jeremy into thinking it was Ralph that had called him in the middle of the night, alerting him to the possibility that Sheila had got the gun, and that she was going crazy, when all along it had been the cousin who had made the call to Jeremy from the farmhouse...