The minimum research period for a PhD is 3 years full-time and 6 years part-time.
During your period of research, you will have two supervisors.
At the end of your research period you will be expected to have completed an extended thesis of up to 100,000 words, demonstrating evidence of your capacity to pursue scholarly research independently. The thesis must make an original contribution to knowledge and be of a standard appropriate for publication in a quality, peer-reviewed learned journal of international standing. You would normally expect a PhD thesis to contain the equivalent of at least three articles publishable in such a journal. You will also be required to defend your thesis at an oral examination or 'viva' normally conducted by two examiners, usually one internal and one external to the University.