I think that there are certain IMGs who are at a particular disadvantage, namely, those who come from develping countries. If you look at many "top" programs, you will often find at least one IMG from places like England, Spain, France, Germany, etc. You will rarely find IMGs from India, Pakistan, China or any African or Latin American country. I don't know if this is racism (most applicants from developed countries are white, whereas those from developing countries tend to be black/brown), or if it reflects a belief that developed countries have better medical education. Also, there is the issue of language. Whatever your interpretation, I think it would certainly be possible for you as UK graduate to match at even the top-most programs, assuming that you do well on the USMLE, etc. BTW, what is the area of your master's degree?