Uhmm i maybe wrong..but I am in UK HE, and I am presuming ur questions are about a UK phd..sont know for other schools, but its probably the same for most schools in UK HE, but a phD entry probably needs a Masters and a 65% plus on that...
May differ, others can help...i go one of the 'trinity' as some say/said of US HE institutions for academics, and its that way for us...I did my mSc from here, and went on with a phd in the same dept, but my offer was conditional tilll yesterday when my 65% or above overall and distinction was confirmed (marks will be released later)...