One purpose of the PhD course is to demonstrate the student's ability to complete a project in a given time. PPARC and the University set upper limits for this. PPARC funding lasts for only three years, and they set a time limit for submission of four years. If this latter limit is exceeded, the Institute may be penalized by a reduction in studentships, making it harder in future for students who want to do research here. Consequently, the University also sets a limit of four years - candidates exceeding this limit have to pay a continuation fee, currently £400 per annum.
The Institute expects that theses will be submitted as soon as possible after the minimum period, and should certainly be submitted within three years and three months after starting. Students who over-run this limit may have their username removed from the ROE computer system unless a good case can be made on their behalf.