(1) For the purposes of this Part -
"liable person" in respect of a relevant site, is, subject to section 653 and 653AI, the owner of that site on the liability date;
"owner" in relation to land, means - (a) in relation to land that is registered land within the meaning of the Registration of Title Act 1964, the person registered as, or deemed to be registered as, the owner of the land under that Act, (b) in relation to all other land, a person, other than a mortgagee not in possession, who, whether in his or her own right or as trustee or agent for any other person, is entitled to receive the rack rent of the land or, where the land is not let at a rack rent, would be so entitled if it were so let, or (c) a person who holds any estate, interest or right in accordance with which that person may carry out development on or to the land.
(2) The absence of documentary evidence, or the disputing by or on behalf of a person (in this subsection referred to as the 'disputant') of the
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