Self explanatory really...what the hell happens if you do??

I have heard of cases of people who have failed but don't know of anyone personally. I would like to think it is relatively rare as it hardly reflects well on the supervisor etc.

I had these worries myself but I think the mock viva helped as well as this forum! I would recommend reading the Tinkler book that someone else suggested on another thread. I also went to a Uni session about the mock viva and that was really useful. They outlined the possible options (e.g. pass no corrections, minor, major, mphil etc etc).

I believe a student from my department had her PhD rejected and then decided to submit an MPhil after 3-4 years. I don't think it is common though.

A friend of mine had to re-submit and have a 2nd viva, all a bit of a nightmare really (major issues with external examiner and some very unprofessional behaviour...). She got her PhD in the end, took an extra year though.