There's no such thing as a "top uni" for medicine. The GMC considers all medical schools they accredit equal, and the NHS is the only provider of graduate training posts for medics and likewise takes the same stance - and to ensure this is upheld, the NHS blinds recruiters from your medical school to ensure there is no bias.
Medical schools should be selected on the basis of how well one's profile fits their shortlisting methodology and if you like their specific teaching style/structure (e.g. PBL, early clinical contact, etc). Not on irrelevant notions of whether one is "better" than another, because that's not how it works in medicine.
Note I believe some medical schools don't even read the PS, and quite a few don't score it at all. So you (or "your friend") are focusing on the wrong aspect of the application really in most cases. Applying to medicine is about ticking boxes - focus on making sure you actually have ticked all the necessary boxes. If you have surplus time then reflect on your work experience and write about those reflections in your PS.
No university wants to see a PS that is just a list of things you have (purportedly) done without any critical thought or reflection by yourself on those.