My experience is that London does it by status (GGL first. The man at the GF lounge told me that they were doing 97s first, but mine might be possible later as I was a 66. He didn’t say what the numbers meant but obviously I knew he was referring to CIV).
The return flight outstations tend to FLUB people who don’t have seat allocations, as you say.
ANU definitely (or at least used to) seat shift based upon status before OLCI opened. It used to be they then opened up the FLUB section once Golds and above had been moved but in recent years they've been closing it out and not reopening it.