Cathay sometimes runs ex-U.K. promotions which while not spectacular might reduce the price - there was one recently for two people booked together on the sort of U.K.-H.K.-Asia itinerary you have. As the above posters said, though, the price you mention is pretty competitive for ex-MAN and the longer you wait the more risk it will go up though could go down.
Personally ex-MAN I'd also suggest considering Singapore Airlines and Turkish (and of course many Brits seem to favour Emirates), but each to their own.