See osm.org/note/206249

These aren't public footpaths. The highest conceivable access rating is destination, but I think they are probably best considered private. As such, they are difficult to, legally, verify on the ground.

The whole estate is NHS land and not a public highway.

This effectively reverses a change I made. I believe it is incorrect to map a path on top of a pedestrian area. The paths were already linked by the pedestrian area, both on the map, and in real life. If routing software cannot cope with that, the routing software is at fault.