(4)If, from the application or from the medical certificate referred to in sub-section (3), it appears that the applicant is suffering from any disease or disability which is likely to cause the driving by him of a motor vehicle of the class which he would be authorised by the learners licence applied for to drive to be a source of danger to the public or to the passengers, the licensing authority shall refuse to issue the learners licence :Provided that a learners licence limited to driving an [adapted vehicle] may be issued to the applicant, if the licensing authority is satisfied that he is fit to drive such a carriage.
