No 6 lives on the 6th floor of a block of flats that is narrower at the sixth floor upwards than the floors below.
No 7 lives on the 7th floor, directly above No 6.
No 7, thinks this is an excellent idea and decides to apply for planning permission to build something ontop of the roof of no 6’s extension…
No 6 cries “You can’t do that!”
No 7 cries back “Of course I can!”
No 6 barks louder ” No you can’t! The airspace above floor 6 is mine! I can build a roof terrace over it, and more!”
No 7 barks back ” No! Its not yours! Your building permission only covers until the vertical height of floor 6, not over and above, at the height of floor 7!”
And off they went, to court, to sort out their differences as to whether there was a presumption that No 6 was entitled to a column of air above his extension:
Judge says No 7 is right. No 6 can’t own the air above his extension, and in any case, it would be absurd to allow No 6 a roof terrace, when this space is directly in view of no 7’s bathroom.