The connection times from the BA7409 into HKG and onto the BA 26/28 are reasonably lengthy at almost 6 hours, and QF operate the A330 with their first generation lie-flat skybeds on the Asian routes (until they complete the J upgrade of these birds in mid-2016). The CX codeshare between BNE and HKG operates via CNS so not that attractive a proposition - but they do have flat beds as CX class it as long haul so the equipment swaps are not an issue.

I'd clearly like it if BA offered a BNE-LHR option on BA metal but I think it's unlikely - they will happily sell you a ticket on a QF codeshare to SYD, SIN or HKG to pick up the relevant BA flights.