Clause 7 allows the Secretary of State to compulsorily purchase only the subsoil or under-surface of land within the Bill limits for work such as tunnelling. Where the Secretary of State only acquires the subsoil or under-surface, he cannot be compelled to purchase the surface land, except where sub-surface acquisition includes part of a building, such as a cellar, and would therefore have a material detrimental impact on the remainder of the property.
Subsection (4) introduces schedule 11, which in specified cases restricts the compulsory powers of acquisition to subsoil or under-surface of land and the imposition of restrictive covenants. The table in the schedule details land where only subsoil more than nine metres below the surface can be compulsorily acquired. This is mostly for deep tunnels.