VISITOR VISA APPLICATION TO ATTEND GRADUATION CEREMONY

Hi, All please give your valuable reply and suggestion on this matter. My cousin already passed his MBA from Cardiff Metropolitan University's Malaysia campus. Cardiff University is giving the opportunity to their students who have completed the course in their international campus (outside the UK) to come to the UK for their graduation ceremony. He has got an invitation request from the Malaysia campus and approved invitation letter from Cardiff Metropolitan University as well. Now the question is whether he can apply for a visitor visa on the basis of these invitation letters? OR should he have to produce any other documents? What are the documents he should submit along with the invitation letter? Kindly advise. Looking forward to hearing from you at the earliest.

Usually the applicant has to show his strong ties with his home country or country of legal residence such as property, savings, business, studies, visa etc