This bit is wrong
"Sash windows do not open silently either, but Bamber managed to get into the house without alerting either the labrador in the garage or his mother’s dog indoors. After gaining entry, he took the kitchen phone off the hook, disabling all the farmhouse telephones, including the one on Nevill’s bedside table"
The phone wasn't in the bedroom on the night of the murders.
I did note that Len Foakes said he 'saw' Neville bringing the trailer back full of rapeseed - so that settles that.