Why are so many Brits now speaking with a strange Gangster Rap style accent?
Sounds obnoxious, but I’ve never witnessed this before. If it sounds Jamaican, though, it may come from the fact that there are a lot of Jamaicans in London, which means it isn’t derived from “gangster rap” at all. And to me it doesn’t seem like it would be Jamaican sounding, or at least not how you described it.