I recall closing an unrelated note at Kai Tak 1331. I closed it because we can't survey it (access=private), and we can't armchair it (YouTube is not a usable source). No pathway exists.

Here, we may potentially survey this by triangulation (may be difficult), or armchair this by using appropriate maps. It's unclear whether we really have no pathways here, so we should in principle keep this open.

For the Crown Copyright, this may require legal research, but preliminarily from the outer layer of my non-lawyer mind, it seems to me Crown Copyright is simply unrevokable / untransferable, and no other contracts or agreements may cancel /sidestep the Crown Copyright, but the CC itself may still expire at some point. From this, older British documents may still be used for OSM editing, but as mentioned several messages ago, it's currently unlikely to find CC-expired maps for this, so this basically becomes a waiting game.