(4) A data controller is not required to comply with paragraph (1)(c) in any case where the disclosure of the personal data to a third party consists of the third party’s own inspection of a register— (a) in which the personal data is entered or otherwise recorded; and (b) which is available for inspection by the public. (5) Where a data controller is requested to correct personal data under subsection (1) of section 17 and the personal data is being processed by another data controller that is in a better position to respond to the data correction request— (a) the first-mentioned data controller shall immediately transfer the data correction request to such data controller, and notify the requestor of this fact; and (b) sections 17, 18, 19 and 20 shall apply as if the references therein to a data controller were references to such other data controller. 19. Circumstances where data controller may refuse to comply with data correction request.- ​(1) A data controller may refuse to comply with a data correction request under section 17 if— (a) the data controller is not supplied with such information as it may reasonably require— (i) in order to satisfy itself as to the identity of the requestor; or (ii) where the requestor claims to be a relevant person, in order to satisfy itself— (A) as to the identity of the data subject in relation to whom the requestor claims to be the relevant person; and (B) that the requestor is the relevant person in relation to the data subject; (b) the data controller is not supplied with such information as it may reasonably require to ascertain in what way the personal data to which the data correction request relates is inaccurate, incomplete, misleading or not up-to-date; (c) the data controller is not satisfied that the personal data to which the data correction request relates is inaccurate, incomplete, misleading or not up-to-date; (d) the data controller is not satisfied that the correction which is the subject of the data correction request is accurate, complete, not misleading or up-to-date; or (e) subject to subsection (2), any other data controller controls the processing of the personal data to which the data correction request relates in such a way as to prohibit the first-mentioned data controller from complying, whether in whole or in part, with the data correction request. (2) Clause (e) of sub-section (1) shall not operate so as to excuse the data controller from complying with subsection (1) of section 17 in relation to the data correction request to any extent that the data controller can comply with that subsection without contravening the prohibition concerned. 20. Notification of refusal to comply with data correction request.- ​(1) Where a data controller who pursuant to section 19 refuses to comply with a data correction request under section 17, it shall, not later than thirty days from the date of receipt of the data correction request, by notice in writing, inform the requestor— (a) of the refusal and the reasons for the refusal; and (b) where clause (e) of sub-section (1) of section 18 is applicable, of the name and address of the other data controller concerned. 12