Generally speaking, under employment law you are not obliged to provide a reference for a former employee.
However, certain sectors and certain job roles do require former employers to provide a reference, Health and Social Care being one of them. If the employee works in a role which requires a reference to be given you must take reasonable care to ensure that the information you provide is fair and accurate, and not misleading.
Generally speaking its acceptable to simply confirm the person’s role or job title, and their date of employment.