A completion notice shall not take effect unless and until it is confirmed by the Secretary of State.

In confirming a completion notice the Secretary of State may substitute some longer period for that specified in the notice as the period at the expiration of which the planning permission is to cease to have effect.

If, within such period as may be specified in a completion notice (which must not be less than 28 days from its service) any person on whom the notice is served so requires, the Secretary of State, before confirming the notice, shall give him and the planning authority an opportunity of appearing before and being heard by a person appointed by the Secretary of State for the purpose.

If a completion notice takes effect, the planning permission referred to in it shall become invalid at the expiration of the period specified in the notice (whether the original period specified under section 61(2) or a longer period substituted by the Secretary of State under subsection (2)).

Subsection (4) shall not affect any permission so far as development carried out under it before the end of the period mentioned in that subsection is concerned.