May an employer ask a prospective employee to fill in a medical questionnaire?

An employer may ask a prospective employee to complete a medical questionnaire, although it should not do so until after it has made a job offer. There should be a statement on the form that the information obtained will be processed by the employer, and a place for the job applicant to sign to signify his or her consent to this. Information about an individual's physical and mental health is regarded as "sensitive data" under s.2 of the Data Protection Act 1998, and the Act requires the individual's express consent to be obtained before such information is processed.