Sch 15 para 20
(1) If a general vesting declaration under this Act comprises part only of a house, building or factory, or of a park or garden belonging to a house, any person who is able to sell the whole of the house, building, factory, park or garden may by notice served on the acquiring authority (in this Part referred to as a “ notice of objection to severance ”) require them to purchase his interest in the whole. (2) Except as provided by paragraph 29, a notice of objection to severance served by any person shall not have effect if it is served more than 28 days after the date on which the notice required by paragraph 4 above is served on him.