Indeed. Homosexuality is illegal in Malawi; some Kenyans have recently formed lynch mobs; Uganda’s got a bill proposing to punish gays with life imprisonment or the death penalty. Obviously, people who become refugees because they’re gay are dangerously disenfranchised in their home country. (And then there are refugees who are already refugees and are also gay, who, between their geographical/political exile and their sexual exile within their own exile communities, are possibly the most disenfranchised population on the planet. The Karen refugees from Burma I lived with were so homophobic that they claimed homosexuality didn’t even exist in their culture, though gay Karen activists would certainly take issue with that claim. See also this great 2002 New Republic article about gay Palestinian refugees.)
In the United States, sexual orientation has been grounds for asylum since 1994 (though plenty of applicants encounter obstacles in the granting process). Hopefully Cameron will use his position to actually follow through on his rhetoric. After he broadens the scope of it—Africa is certainly not the only continent on which gays are persecuted.