As I read it, the connection was never subject to the rule. Thus, EDI-LHR-HKG would get the F/CW/WTP allowance if the second segment is in one of those classes of service. This is about stop overs and returns.
But, bear in mind that BA's internal policies are superceded by US law on tickets to or from the US. On these tickets, the base allowance for the marketing carrier of the first segment applies to all segments of the ticket out and back. Note that base allowance does not include waivers for status.