Falklands/Malvinas latest, help from God sought.

Hong Kong was only on 'Lease' to Britain, the contract stated when & on what terms that 'Lease' would end.

No it wasn't, I suggest you check the terms of the leases and which territories they covered.
You will no doubt note that the walled city in the new territories was never leased to Britain and that Hong Kong island itself and the land south of the new territories were not under lease from China.