7Where personal data are held for historical, statistical or research purposes and not used in such a way that damage or distress is, or is likely to be, caused to any data subject—
(a)the information contained in the data shall not be regarded for the purposes of the first principle as obtained unfairly by reason only that its use for any such purpose was not disclosed when it was obtained ; and
(b)the data may, notwithstanding the sixth principle, be kept indefinitely.