For instance if my MA was in Renaissance Literature and I wanted to begin a PhD beacuse I had an idea for a PhD in, say, 20th century American Literature. Would a university accept me if my proposal was sound?

Any advice would be very welcome, thanks.

Anyone... Please?

Literature isn't my discipline so can't comment specifically, but lots of people change their direction from Masters to PhD and make much bigger leaps than moving from one genre of literature to another. I wouldn't foresee how admissions/potential supervisors would consider it a problem if you presented a well-researched proposal.

I changed discipline too. My Masters history degree was rather different from my PhD history topic. So much so that it gave me virtually no grounding in it! But it hasn't been a problem, either at admission or since.

A friend of mine has just finished his MPhil and was set to do his PhD in the same department. His research for the proposal showed that his chosen area was not feasible for that level of research. I'm not sure what led him to changing subjects, but it meant he had to go to another university. As he has no academic background the place was on condition that he completed an MA first. It adds to his time there, but as its important to him then it doesn't matter.

If you can fully explain the reason for your subject change etc (as well as having a good proposal!) then I can't see why they wouldn't accept you. Have you approached someone in the department to discuss the matter. Having someone as a possible supervisor would help your application when it went infront of the panel.

I also know of people who've had quite major changes in direction from their MA to the PhD, so I'd say that if you have a good, strong proposal and a supervisor lined up who supports you then it shouldn't be a problem. You wouldn't be using many of the same research techniques and studying within the same discipline, its not as if you have a humanities background and attempting to transfer to science or social science. Do try to meet with you potential supervisor though and discuss you ideas fully with them and see what they feel.

Definitely. IF you got good grades, a good ref. then you'll be able to. I'm swapping disciplines for my PhD. You're still in literature so it won't be a problem, but you will need a good proposal which suggests that you know your American lit. Good luck