4. Regulations may make provision as to circumstances in which—N.I.
(a)a lessor is to be taken for the purposes of Article 32 and this Schedule to have—
(i)withheld his consent;
(ii)withheld his consent unreasonably;
(iii)acted reasonably in withholding his consent;
(b)a condition subject to which a lessor has given his consent is to be taken to be reasonable;
(c)a condition subject to which a lessor has given his consent is to be taken to be unreasonable.