i have an ordinary MSc(Pass) degree from a UK university and i want to proceed for my PhD. I have sent 2 good proposals to potential supervisors and they are willing to supervise. Unfortunately, I got a mail from their research school that my MSc grade is low and they cannot give me an offer. Does it mean that i cannot proceed for PhD with that MSc grade or do i try another school ? Please advise.
Amawo

Try another school. Everyone has their own admissions policies

What TreeofLife said. Try another school. Speak to the supervisors, and explain the situation, they can and often do bend the rules for candidates they feel are worth the trouble. Alternatively, they can also introduce you to other prospective supervisors that might be interested, both within and outside their own respective institutions.

Something somewhat similar has happened to me too. I have a good M.Sc. in engineering, but I applied to the mathematics department. I had written my proposal in applied mathematics, and the professor was willing to supervise me. We even had technical discussions by email back and forth, exchanging literature and coming up with ways to pursue the project. But when I sent in my application, it got rejected because priority for the admissions at the department is given to people with M.Sc in maths. So it didn't work out, even with a willing supervisor and good proposal.
Yet, I know people at other universities who have done this. Just down to different admissions policies.