Alright, so as the title implies, this is a what if about Britain holding onto Hong Kong, it's not an AHC, so no need to talk about probability or anything. Just chalk it up to having a permanent lease.
That dealt with, what would the impact be? How would Britain's role in Asia be changed? Would they be regarded as more of a world power? Could Hong Kong be integrated over time into the union as a normal part of it?