s 138 Circumstances in which land incapable of reasonably beneficial use.
(1) Where, for the purpose of determining whether the conditions specified in section 137(3) or (4) are satisfied in relation to any land, any question arises as to what is or would in any particular circumstances be a reasonably beneficial use of that land, then, in determining that question for that purpose, no account shall be taken of any unauthorised prospective use of that land. (2) A prospective use of land shall be regarded as unauthorised for the purposes of subsection (1)— (a) if it would involve the carrying out of development other than any development specified in paragraph 1 or 2 of Schedule 3; or (b) in the case of a purchase notice served in consequence of a refusal or conditional grant of planning permission, if it would contravene the condition set out in Schedule 10.