Beef rump

Are you looking for medium to medium rare?  You could pull it a few degrees early and let it sit for a ½ hour before carving.  Time is hard to tell, a lot depends on the meat itself, the marinade you use, etc. so a precise time is difficult, but I would say that would be a good ballpark figure.

The other secret to a great roast is to slice it correctly.  Put it face down, fat side up.  Then, when carving, start at the tip (pointed) end and slice diagonal to the grain, which you should easily see on the non-fat side, even if it a slice or two to get started, then flip it back over fat side up and continue slicing in that manner.  Your roast will be tenderest that way.