The Secretary of State may with the approval of the Treasury alter, enlarge or rebuild any prison and build new prisons.

The Secretary of State may provide new prisons by declaring to be a prison any building or part of a building built for the purpose or vested in him or under his control.

A declaration under this section may with respect to the building or part of a building declared to be a prison make the same provisions as an order under the next following section may make with respect to an existing prison.

A declaration under this section may at any time be revoked by the Secretary of State.

A declaration under this section shall not be sufficient to vest the legal estate of any building in the F1Secretary of State.