All the evidence points to Bamber climbing out of the kitchen window -
He said he knew how enter/exit the kitchen window.
The housekeeper said crime scene photos showed fixed items around the kitchen window had been moved.
One of the kitchen window locks could be banged shut from outside.
The horizontal lock could not be banged onto it's pegs from outside. This lock was found off it's pegs which would not be the case if June/Neville had shut this window.
Julie testified that Bamber had told her he had found a way out of WHF and secure the same window from outside.
There is no evidence that JB exited through the kitchen window.
Even if it was possible to exit and secure the window when outside it is only proof that he MAY have exited that way.
It proves he or someone else had the ability to enter and exit the farmhouse via that window or by some other means such as the upstairs window.
However all the court required was proof the house could have been entered, secured and exited somehow.
The fact the finger was pointed at JB was due to the phone call from Nevill which made it clear either JB or Sheila or both were responsible for the killings.