Julie didn't get the following from the newspapers -
Low house insurance.
Bible by Sheila.
Sheila's shot locations.
Kitchen fight.
Twins asleep.
Sheila putting up no resistance.
Nevill's multiple shots.
June shot in bed.
Kitchen windows.
Portable phone.
Mason clock.
Twins shot first.
Sheila shot last.
June's sleeping pills.
Sheila & the twins sleeping in different rooms on different nights.
Kitchen argument.
Shooting rabbits.
Sheila shot on parents bed.
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With most supporters ruling out an industrial frame, she could have only got this information from Bamber or the relatives.
It is very unlikely the relatives would be able to get this information within a month. And very unlikely they would decide to pass it onto Bamber's girlfriend, who could warn him.
It is also very unlikely the relatives would be able to contact her as Julie was constantly with Bamber.
So Julie could have only got this from Bamber.