Just a thought from trying to turn what seems a negative..into a positive...
What if GBC became nasty or violent with this Sydney woman??...she'd report him or hike it quickly back to Sydney??..
Now that would be a nice little bow in Inspector Ainsworth's gotcha bag??
TM is "hiding out", possibly in Sydney (Blue Mountains) where she is from. There may not be a second woman, just Toni, IMO.