Metwin1, I think it's obselete UK-English; it's the kind of usage you'd find in a 1920s book about boys at a public school (ie posh private school, in anyone else's parlance
). I have vaguely heard of the expression 'mugging up on a subject'. Certainly no-one uses it in that sense any more; and neither is 'cram' used in the sense of studying or revising for exams.
Wendy
