THE gate of course. 
Is this a misunderstanding? "2115: JT leaves table, and sees GM talking with fellow resident ("Jez" Wilkins) outside the patio gate of 5A. The two were standing just up the hill from the gate towards Rua A. da Silva Road. She did not speak to GM as she passed."
Could Gerry have made an error in thinking when he signed off on the joint timeline that by gate he meant the The Secondary Reception gate?
Time line: "2115: JT leaves table, and sees GM talking with fellow resident ("Jez" Wilkins) outside the patio gate of 5A. The two were standing just up the hill from the gate towards Rua A. da Silva Road. She did not speak to GM as she passed. "
Should it have read something like "2115: JT leaves table, and sees GM talking with fellow resident ("Jez" Wilkins) outside after Gerry left from the patio gate of 5A. The two were standing just up the hill from the reception gate towards Rua A. da Silva Road. She did not speak to GM as she passed."