(1)A notice to treat served in pursuance of this Act becomes invalid 3 years (or such longer period as may be agreed under subsection (2)) after it is served, unless—
(a)the compensation has been agreed, awarded, paid or paid into a bank (or the question of compensation has been referred to the Lands Tribunal),
(b)a general vesting declaration has been made in respect of the land concerned, or
(c)Ministers have entered and taken possession of the land concerned under section 39.
(2)The period of 3 years referred to in subsection (1) may be extended (and further extended) by agreement between—
(a)Ministers, and
(b)the owner of the land.
(3)Where a notice to treat is invalidated by this section, Ministers must give notice of that fact to—
(a)the person on whom the notice to treat was served, and
(b)any other person who, since it was served, could have made an agreement to extend under this section.