The aerial photo is one I've got as a sort-of-average A4 print - it lost a bit in the downsizing but most of the detail is still there. I put it up because I've never seen it around on the web before.
Here's one that I have seen on the web in a number of places, and that I don't have a hard copy of, but it seems to fit in this thread nicely. I used to think that it was the return of the wall at Harrison Drive, with the Lifeguard Station where the crane is on the left of the picture, and was therefore part of Phase 2.
Now I'm not so sure. I think it might be the 'return' to land of the phase 1 wall that's visible at the top of the aerial photo I posted above. That had a slipway (which would have looked similar to the existing Harrison Drive one), and was located just west of the twin slipways at Portland Street.
As I mentioned, the lower parts of that wall were buried beneath the dips when the wall was continued to Harrison Drive. Note the rock outcrop in the lower right foreground - that's one reason I think it's the now-buried return wall.
I think you are right. The top of the rock outcrop is still visible
surrounded by grass and the photo seems to have been taken from the
clifftop judging by the angle. So it's the Red Noses not Harrison Drive. Very interesting stuff.