Data Protection Act 1988
Right to establish existence of personal data.
3.—An individual who believes that a person keeps personal data shall, if he so requests the person in writing—
(a) be informed by the person whether he keeps any such data, and
(b) if he does, be given by the person a description of the data and the purposes for which they are kept,
as soon as may be and in any event not more than 21 days after the request has been given or sent to him.