I am myself a medical student at Imperial, having just finished my second year and going into my third. I personally found getting into medicine very difficult.
The lowest grade I have ever achieved in a public exam is an A grade, this is both in total and modular grades. I sat both the UKCAT and BMAT and got decent grades in both. I had all the volunteering down, I founded the debating society at my school, was an academic prefect in mathematics and french, and a senior tutor to kids in the surrounding primary schools.
I had always been adept at logico-spatial and mathematical subjects, and this was reflected in my A levels grades (where I got much higher scores in physics and mathematics than I did in biology and chemistry). I also started a natural sciences degree prior to my medical course with the open university, having done modules in things like molecular genetics (which I had an out of date copy of on my profile).
I had and still have an interest in social science, and was selected by competitive admission to attended the Harvard Model United Nations, as part of the Trade and Development Committee in the 2011 assembly, and have also done an extracurricular course in classical philosophy. I didn't get flat out offers from my applications, and gave interviews of varying quality.
I post only in rebuttal to a few points. Medicine is a hard course (at least for me anyway)- its as much about learning though the understanding of systems in neuroscience, pathology, oncology, pharmacokinetics and pharmacodynamics, immunology -and so on- than any science subject I had personally come across. The second thing is that those of you doing other degrees who believe you will be doing research "at the forefront of your field" underscore a phenomenal lack of foresight. It's really, really hard to do research at the forefront of your field, and I say this from talking to friends who find doing this exceedingly difficult who are on full scholarships to both Harvard and MIT.
Secondly, biomedical students- whilst they do important, exceptional and corollary research to that carried out by medics, most research done in hospitals that I am aware of is carried out by doctors. In the London trusts, you cannot get a consultant post in surgery unless you have a PhD. Some of the doctors at our trust (such as Lord Darzi) have personally piloted fields such as robotic surgery (infact darzi received an honorary engineering degree for this). Memorizing facts can work, but up to a breaking point- one which appears early in medicine, and I've seen friends I care for dearly crack under the pressure and leave, due to their failed attempts at "memorising" medicine. It's too much if you do it that way. Some might?
Also most learned people can tell you the basics of MRI scanners- that was covered in GCSE and then again in A levels. Yes a physicist at Harvard produced the first ever one-dimensional MRI. Physics is awesome. And you might know more about it as a physicist- but you can't interpret it.
I've never felt more attacked for doing medicine, and I'm quite saddened by it, tbh.