Not sure what your point is Dave, I know this can be done structurally speaking, I'm not sure whether the Brizzy planning authorities work to the same rules as UK Councils and by the looks of it, that road looks very much like a public road so the planners are likely to be the ones that would give permission for a flying freehold over their own land (and give outline/likelihood of permission of this at an early stage).
The land next to ours is privately leased, there may be covenants on it about sub letting o other permissions of use, changes to these may be time consuming, United Utilies may have their own plans for it and don't have to give any indication beforehand of what their decisions may or may not be.
We could have banged in an application to do this, applied for a compulsory purchase order that United Utilities contest and we would still be at the planning stage now, rather than looking at building work racing along.