This view is of the quarry wall running alongside the B225 looking north to south. The probable tunnel hole seems likely to be right at the end of the curve, out of vision.

This is a tunnel entrance from Western Quarry (Bluewater side) that leads through to the Eastern Quarry. It may (or may not be) the other side of the tunnel that serves as the Daleks' mine in Dalek Invasion of Earth.

This view is of the quarry wall running alongside the B225 looking south to north. The probable tunnel hole (matching with Bluewater) would be just out of sight near the bottom.