That would be the interconnect you are using to reach Zens core network, presumably where the PPP session terminates. In theory, it will be the nearest exchange that has a direct connection to Zen, Colchester perhaps?
Mine says nge001.don-re0, so maybe Doncaster? Completely guessing here.
Checking on SamKnows, both those exchanges are showing Zen LLU which adds further weight to this theory.
Zen only have NNIs/interconnects to BT Wholesale in London and Manchester. What you're seeing there is the first PPP device in the chain, the one you pre-authenticate against to be directed to Zen.
Your PPP session ends on the Zen network. There is no BTW broadband product that'll deliver connectivity to a bunch of LLU exchanges, the NNIs have ranges and a limited number of nodes customers can be connected via.
Your PPP session goes into an L2TP tunnel when it hits the NGE / BRAS, and gets switched across LTS / L2TP Switches until it gets to Zen, where it lands on the Zen LNS.
The connectivity Zen have in exchanges is to Openreach not BT Wholesale.
EDIT: NGE seems to say some other backhaul to me, maybe TTB? The kit in BTW exchanges are usually named MSEs and I'm fairly sure there are MSEs in Intake.
Similar applies either way - you don't get onto the Zen network until you reach an NNI, London or Manchester, where the Zen LNS live.