If Nevill needed help in calming Sheila down by talking to her, he would use June. As she was inside WHF.
Saying Sheila & June did not get along does not work as they were in regular contact with each other.
Bamber said on the night Sheila was a looney, nutter, do lally, is having treatment; should be locked up & didn't like him. He later said he did not understand her illness. So would be of no use in helping Nevill calm her down via talking.
Bamber was also 3 miles away at 3.00am. Nevill ringing his AM will just agitate Sheila more.